LIBRARY OF CONGRESS. 



Shelf ..Ji..'7 

UNITED STATES OF AMEEICA. 



TEACHER'S MllNUIL 



EXPLAINING THE USE OF 



CHSS. ¥. HOLBROOK'S 



LUNAR TELLURISl 



7P 




PRINTED FOR THE AUTHOR BY 

The Case, Lockwood & Brainard Company, Hartford, Coxz 



copyright, 1888, 
By Charles W. Holbrook. 



\A 



PREFACE. 



TEACHING is to some extent, as the genial Dickens makes Man- 
tellini say, '' one demd horrid grind." 

The wear and tear, the dull routine, the hopelessness of dull minds, 
the mechanical aspect of the teacher's life, the hard work and poor 
pa}^ of the noblest calling ; these facts have been constantly upper- 
most in my mind, lending zest to an endeavor to help the teacher. I 
should consider the mere inventing, patenting, making, and selling 
of my Tellurian an ignoble aim unless the desire of an income were 
in some measure transfused by an attempt to lighten the burdens of 
teaching. Surely to inspire a mind with zeal for self-improvement is 
a lofty act. To effect a permanent lodgment in a human brain an idea 
must be illustrated by a mechanical fact when possible. To govern 
and administer a school is a rare talent — developed in many teachers, 
latent, however, in the most cases. The idea of law, system, obedi- 
ence^ has its origin in nature — there and there only can we fmd the 
evolution of the idea physically illustrated in what we call the phe- 
nomena of nature. When a teacher can close his eyes, transplant 
himself into space, and see the earth pursuing the mysterious round 
of rotation and orbit — the tiny moon swimming and circling in her 
endless journey of subjective obedience to the greater orb ; all facts 
of primary astronomy become instantly apparent. He has then but 
one use for this mechanical instrument, viz.: to x>'^^<^^^ to the unde- 
veloped imagination the invisible facts as seen by himself through 
the visual process of mental insight. Enthusiasm supplants the 
mere sense of routine duty, original illustration by means of the 
pencil, chalk, diagrams, etc., occur as the pupil catches the infection 
and asks questions, and it goes without saying that one hour of 
genuine enthusiasm in a class is worth a whole term of dragging, 
monotonous repetition of words. 

For their own sake and the benefit of the class, then, the writer asks 
teachers to give this little book some real attention. It makes no 
pretensions to literary or any other merit than as a help to the tired 
teacher, whose aims and aspirations and disappointments and suc- 
cesses have his full sympathy. 

CHARLES W. HOLBROOK. 

(3) 



INDEX. 










Page. 
Apparent Motion, ....... 16 


Real Motion, 










. 18 


Day and Night, 










. 20 


The Sun, 










. 29 


Vertical and Oblique Rays, 










. 30 


Inclination of the Axis, . 










. 32 


Twilight, 










. 45 


Sun's Declination, '. 










. 47 


Change of Seasons, 










. 52 


Climates, 










55 


Longitude and Time, 










68 


Sidereal and Solar Time, 










72 


The Moon, 










74 


Phases of the Moon, 










79 


Harvest Moon, 










80 


Nodes, .... 










81 


Eclipses, . . 










84 


Lunar Journey, 










89 


Tides, ..... 










96 



(4) 



A NEW GLOBE. 

TELLURIAN AND LUNARIAN IN ONE. 

Invented and made by Charles W. Holbrook. 



Patented March 6, 1888. 



MANUAL OF EXPLA:SATI0X WITH EACH IXSTRUMEXT. 




All phenomena of Sun, Earth, and Moon elucidated 
by this simple, accurate globe. 

Xot a complicated, delicate machine to get out of 
order and be set aside for dust and flies. 

(5) 



6 Chas. W. Holbrook's Lunar Tellurian. 

All parts visible and interchangeable should any 
become disabled by accident. 

Not a hidden bolt, bar, or gear; no secreted belts to 
break or loosen. 

Easily adjusted, ready for use, cannot be set up 
wrongly for study. 

Not a long course of practice required to understand 
it. 

Any one can use it and with the aid of the Manual, 
understand natural causes and effects at sight. 

Not an instrument that will catch, hitch, break down 
and stop — embarrassing a teacher before his class. 

Can be absolutely depended upon. The only globe 
which illustrates, with any degree of accuracy, the 
courses of the moon as verified by almanacs; showing 
phases, eclipses, nodes; when, how, and why they occur. 
Has a transparent shade for the dark side of the earth, 
also a shade for the moon, operating exactly as in nature. 
Affords interesting study for class room and library. 

This new Tellurian, Lunarian, Globe, three instruments 
in one, illustrates, with precision, over one hundred 
astronomical conditions; elucidating phenomenal or 
apparent facts and deducing real or noumenal facts. I 
ask your attention to the manual written, especially for 
this globe, in the ordinary language of conversation; 
avoiding, as far as possible, the technical terms of 
astronomy. The greatest obstacle to the general use of 
such a globe is the want of familiarity, on the part of 
teachers and parents, with the mechanics of our solar 
system. They should understand the simple arrange- 
ment by which our world maintains its relations to the 
sun, and the moon to the earth. 



Chas. Vv". Holbrook's Lunar Tellurian. 7 

The mathematics of astronomy is a higher and more 
abstract branch of study known only to the few. 

The inechanical facts are easily understood and in- 
stantly; without any abstruse calculations or great effort 
of the imagination. Among the many the following list 
is given of the mechanical conditions existing at the 
different times and places of the earth in its annual six 
hundred million miles journey around the sun. 

A.— Daily Motion of the Earth on its Axis^ 
illustrating the following facts^ yiz. : 

1. That the sun, moon, and stars do not have the 
movements apparent to the eyes, but that the earth has a 
movement exactly opposite to what appears in the sky. 

2. The division of the earth's surface into sections of 
meridian and parallel and why the astronomers were 
obliged to do this. 

3. Cause of day and night and twilight. 

4. Passage of the hours of a clock dial entirely around 
the earth every day. In plainer words, the fact that noon 
is a condition of a constant and endless duration; it is 
simply the moment when your locality is brought near- 
est the sun by the earth's daily rotation. 

5. The time of day by your clock is earlier than at 
places east of you at the rate of one hour to each fifteen 
degrees; and later than at places westward. 

6. Quantity and conditions of heat emitted by the sun 
— effects of heat upon the earth — difference between 
vertical and oblique solar rays and consequent division 
of the map into Zones. 

7. A device for mountmg the globe so as to show the 
earth with a perpendicular axis, like Jupiter, and 
explanations why seasons would never change, but 



8 Chas. W. Holbrook's Lunar Tellurian. 

climate would vary according to distance from equator; 
days and nights would be 12 hours each, always. This 
experiment is vital to a clear understanding of the real 
significance of an axis inclined as is that of cur earth. 

B. — Inclination of tlie Earth's Axis. 

The plane of the Ecliptic, why so called and its signifi. 
cance. The earth's Orbit or Annual Path. Two primal 
facts bearing vast results illustrated and explained. 

8. Constellations and signs as given in astronomy. 
Their uses and value as sign -posts. 

9. Why the sun is high in summer and low in winter, 
though it never moves. 

10. Sun '^ crossing the line." 

11. Why the day and night are each 12 hours on 
March 23d and September 23d, all over the world and 
at no other times. 

12. Why the sun rises at 6 and sets at 6, every day of 
the year, at the equator. 

13. Why days are not of the same length at different 
places for the same time. 

14. Why days are not uniform at the same places for 
different times. , 

15. Full and exhaustive study on variations, durations, 
and causes of time, with interesting experiments. 

16. The midnight sun at the Arctic Circle. A polar 
day and night, each six months long, with a description 
of the sun's apparent course seen by a man standing on 
the north pole. 

• 17. Difference between a sidereal and solar day. 

is. Description of the sun's constitution, size, and 
importance. 

19. Physical significance of atmosphere — how its loss 
would depopulate the earth in a moment. 



Chas. W. Holbrook's Lunar Tellurian. 9 

20. The theories of Milton and others about the 
inchnation of the axis. 

21. The axis of the earth always true to the same 
direction, called '• parallelism." 

22. Zenith and Nadir, when and where the sun is 
directly above your head, its distance from that Zenith 
for any day in the year. 

23. Change of seasons — why we do not have a 
uniform summer as they do at the equator. 

24. Description of the four seasons, showing why they 
change at distances from the equator without varying 
there. 

25. Why it is summer at all places south of the 
equator during our northern winter, and vice-versa. 

C. — Climate. 

A chapter explaining witli the aid of the globe. 

26. Why the climates of different places on the same 
parallel at the same time are so unlike. 

27. Humboldt's researches. 

28. Alternations of seasons. 

29. Local variations. 

30. Explanation of the red and blue lines on the 
globe. 

31. Effect of mountains, plains, distance from sea ; 
height of land levels, etc.. etc. 

32. Polar and equatorial currents of water and air 
constituting the ocean currents and trade winds. 

33. The Gulf Stream and its effect upon climate. 

34. The myrtle blooms in winter in Ireland, and why. 

35. Sun's distance from the earth at winter and 
summer. 

36. Greater accumulation of ice at the Antarctic than 
at the Arctic reo;ion. 



10 Chas. W. Holbrookes Lunar Tellurian. 



37. How this causes predominating currents of water 
and air thence to the equator. 

38. CiviHzation the result of climate and slow north- 
ward march of human achievement, since the rise of 
Thebes, identical to the northward advance of the 
temperate zone. 




The Lunarian illustrates all facts relating to the 
Moon's courses, some of which may be given, viz. : 

39. The moon's actual motion on its axis. 

40. Face of the moon always toward the earth. 

41. One -half always bright, whether visible to the 
earth or not — the other half dark by rotation into its 
own shadow. 

42. The moon's day and night each 15 times as long 
as our own. 

43. Difference between the moon's sidereal and solar 
days. 

44. The inclination of the moon's orbit, or monthly 
path, to the plane of the earth's orbit or yearly path. 



Chas. W. Holbrook's Lunar Tellurian. 11 

Illustrated by no other instrument with any degree of 
exactness. 

45. Phases of the moon — causes of a '^ full," '^ quarter," 
*^ crescent," and ^' new " moon. 

46. A bright moon with a dark shade, showing the 
actual graduation of phases according to nature. 

47. Why the moon is ''high" in winter and '' low " 
in summer. 

48. Nodes of the moon — mystery made clear. 

49. Conjunction, quadrature, and opposition. 

50. Why the moon must be at or near a node to cause 
an eclipse. 

51. Why solar and lunar eclipses do not occur eve::'y 
month, during the moon's journey around the earth. 

52. Total, Annular, Partial eclipses of the sun — their 
simple causes and effects. 

53. Moon's distance from the earth, called Perigee and 
Apogee, their various effects upon eclipses. 

54. A journey of the moon as described in the 
almanacs, traced, illustrated, and explained, including 
actual eclipses as they occurred. • 

55. Tides, their causes and effects. 



12 Chas. W. Holbrook's Lunar Tellurian. 



Note to Purchasers. 

If you receive the globe with the vioon screwed on the 
arm, all you need to do to complete the adjustment of 
the lunarian is to set the globe upon the central part, 




arranging the other parts as seen in the cut. To take off 
the moon, loosen thumb-screw X, turn to the left by 
grasping at N. When you adjust the mioon, follow 
directions given under the head of ^' Lunar Tellurian," 
in the manual, taking care to have X loose and N 
tightly screwed up. 



CHAS. V/. HOLBROOK'S 

Lunar Tellurian. 




Directions for setting- up theTellurian. 

Place the round base in such a position that Dec. 21st 
will be at your left hand and toward the south. 

Adjust the globe as shown in the cut, move the geared 
arm until the calendar index A is exactly over Dec. 21st. 

(13) 



14 Chas. W. Holbrook's Lunar Tellurian. 

Adjust the short arm B C so that the stud underneath 
will drop into the hole in the gear below. Tighten 
thumb screw C. This movement places the earth in 
true position, from which it cannot vary. Screw in the 
sun wire D, and adjust the pointer E so that the point J 
will indicate meridian 95° (which, on our eight-inch 
globe, runs north through the United States) at the 
point where Tropic of Capricorn, the Plane of the Ecliptic 
and the meridian intersect. The tellurian is now 
rectified for Dec. 21st or Winter Solstice. 

Adjust the day-circle K by sliding the thimble over 
the end of the horizontal geared arm at H. 

Description- 

The Sun is represented by the post D, with its hori- 
zontal moveable wire E ; the latter illustrates the central 
vertical ray of heat, or a straight line from the sun's to 
the earth's center. 

The Sun is not a mere speck of light, but it is so far 
distant that its comparative bulk is out of the question. 
A tellurian constructed upon true astronomical proportions 
w^ould be a huge affair, requiring a wide expanse of plain 
for a class-room. Given an 8-inch globe for our earth, our 
2-inch moon would describe its orbit at 20 feet, while 
our sun would need to be a sphere 72 feet diameter at a 
distance of a mile and a half. 

E J represents the vertical rays and maximum volume 
of heat bestowed upon the earth. If you move the solar 
index E up the post D and project it near the earth, you 
will see that it would, if too near the map, describe just 
such lines as now encircle the earth. 

These Parallels of Latitude are numbered from the 



Chas. W. Holbrookes Lunar Tellurian. 15 

Equator north to the North Pole, and south to the South 
Pole. 

The greatest of these circles, the Equator, divides the 
map of the earth into northern and southern hemi- 
spheres. 

Revolve the globe rapidly and describe these parallels. 
Adjust Solar index as in the cut and let it cover the 
exact point where the meridian of Greenwich crosses the 
equator, observmg — 

1. Parallels of Latitude encircle the earth and are 
used to find distances and measurements east and vv^est 
or Longitude. These distances are measured from a 
line crossing the parallels and extending from pole to 
pole, called the Meridian of Greenwich or Prime 
Meridian. 

2. Meridians are lines extending north and southward 
and are numbered by degrees, beginning at the Equator, 
therefore — 

The latitude of a place is its distance in degrees north 
or south from the equator. The longitude of a place is 
its distance east or west of the Prime Meridian. 

Push the solar index E down to the Tropic of Capri- 
corn and let it rest. Turn the globe on its axis until 
the index covers the point where meridian 95 crosses 
the Tropic of Cancer, and let it rest. 

The Tellurian now illustrates the position of the earth 
Dec. 21st, when it is noon on meridian 95. The Sun's 
vertical rays are at Capricorn, south of the equator; the 
Arctic region around the north pole is enshrouded in 
twilight and darkness; the Antarctic region near the 
south pole is bright with perpetual day. It is winter 
north^ summer south of the equator. 



16 Chas. W. Holbrook's Lunar Tellurian. 
Apparent Motion. 

The unwearied sun, from day to day, 

Does his Creator's power display. — Addison. 

To the human eye the sun at intervals makes its 
appearance upon the eastern horizon, pursues a course 
upward until noon-day, thence downward to night-fall at 
the west, silently sinking to rest. 

Its light is sublime, its silence awful, the calm dignity 
of its course is majestic ! 

The place of rising and setting varies, for we have 

observed that in summer it rises far enough noi'th of 

east as to throw its rays through our northern windows; 

Suivs dinr- setting to the north of west, while at noon its path is 

nal course. . 

traced nearly in the zenith. In the winter its course is 
far to the south. Late it rises from a royal couch far 
away on the southeastern horizon; so far and so late, 
that to us living near the 40th parallel, its daily visit is 
brief. Early in the afternoon it retires, having made so 
short a journey through the sky that its rays give but 
meagre comfort to the frost-bound denizens of the north 
temperate zone. 

And when the evening shades prevail, 
The moon takes up the wonderous tale, 
And nightly to the listening earth, 
Eepeats the story of her birth. — Addison. 
diurnal '^^^ lunar journey is even more various and puzzling 

course. than the sun's, for the moon, apparently, suits her con- 
venience as to place of rising and setting, as well as to 
time; rising, sometimes, close on the heels of her lord's 
departure, as if in hot pursuit ; at others, so tardy in her 
course as to find her light extinguished by his rays, 
belated in the morning sky. Her moods are changeable, 



Chas. W. Holbrook's Lunar Tellurian. 17 

occasionally averting her face with quiet indifference, 
again beaming over the eastern horizon with a round, 
full, silvery stare; often disappearing entirely for sev- 
eral nights. Compared to the sun's constancy, the 
moon's conduct is strange to the extreme, whimsical 
and coquettish ever, yet always resorting to the same 
old tricks. 

Stars of electric brilliancy rise and set, while others, Apparent 

•^ course of 

less bright, are fixed; though each night their groups the stars, 
seem to have moved shghtly westward. 

The uniformity of the movements of these heavenly 
bodies — sun, moon, and stars — is deceptive. It is not 
easy to believe that the sun stands still, while the earth, 
whirlmg on its own axis at a rapid rate, performs a 
yearly journey through space, passing completely around 
the sun in an orbit of immeasurable magnitude. 

What though in solemn silence all, 
Move 'round this dark terrestrial ball? 

is the poet's expression of apparent motion. We are 
sure the sun moves daily through the heavens, for we 
have all our lives watched its coming and going. The 
features of our landscapes have become as familiar to us 
as the sun's course. Are not we, our home, our nei2:h - Familiar 

. ? aspects. 

bors, our hills, plains, valleys, the winding river which 
forever runs toward the sea — are not these firm and 
immovable? The forest, whose darkening shades nerved 
us to quicker steps as we hurried home from school, the 
sun going down, still casts a long wintry shadow, or 
resounds with the songs of birds in summer. Later in 
life we sped through its depths behind jingling bells, our 
boisterous shouts waking lonely echoes, and startling the 
fox, squirrel, and rabbit. 
2 



18 Chas. W. Holbrook's Lunar Tellurian. 

We had seen the sun set and were glad, because we 
preferred the superb great white moon riding high in the 
heavens, and illumining our wintry landscape. 

Visit the home of an aged resident and hear him 
recount the old ways, describe old landmarks. If a 
house has been lost by fire or flood does not the site 
remain ? If the forest has succumbed to the axe of 
progress does not the site remain, even though covered 
Fixed fea- bv a thrivins; city ? Have the hills been removed and 

tiires of the y . ^ . . 

landscape, the river stopped in its course ? Yes, the fixed features 
of nature remain in the same relation to each other ; 
your houses, farms, prairies, towns, counties, and states 
are always the same. Ascend the White Mountains and 
you will ever catch a glimpse of the sea ; descend the 
cailon and see the sun for a brief space at midday ; take 
ship for foreign lands, sailing whither you will, when 
you return all the facts of nature are the same. 

Man accomplishes much, but he cannot change the 
actual geography of states ; he can simply change names 
and titles. The sun, moon, and stars apjDear to rise and 
set ; yet the fact is that the sun is at rest, and you, with 
your house, farm, landscape, your journey round the 
earth, all are forever in motion at the rate of thousands 
of miles every hour, every moment. 

Daily experience affords many illustrations of apparent 
motion. The facts of real motion are mathematical and 
cannot be gainsaid. Apparent motion is a phenomenon. 
Eeal motion is a noumenon. 

Real Motion. 

Modern astronomy has shattered the lying heresies of 
antiquity. The simple cosmogony which is based upon 



Chas. W. Holbrook's Lunar Tellurian. 19 

human vision has l3een displaced by a grand mathe- 
matical science, prolonged study, and the telescope. 
Only great efforts of the mind and a severe struggle 
against the evidence of our senses can convince us that 
the earth moves, instead of the sun. Not until the last 
century did the truth penetrate a human mind, but since 
that time great progress has been made. To-day the 
astronomer, fortified with his scientific knowledge, gifted 
with constructive imagination, closes his eyes for a mo- 
ment and sees by mental vision the actual motions of 
planets, satellites, systems so complex that a verbal 
description is a mere mechanical form of speech. 

The Sun is the source of light to our solar system. Sun. 
Backward, through all the countless ages, aeons, cycles 
of time, his rays have benefited worlds ; through un- 
born futures he will continue to confer this boon. Eter- 
nally he shines ; illuminating any opaque object within 
reach of solar rays, bestowing to planets the opposing 
forces of light and darkness. 

Planets are illumined according to size and distance illuminated 
from the sun. The earth receives light upon one-half its spheres, 
spherical surface, that is, an astronomical division of the 
earth in two equal hemispheres might be made, and one 
would be always light, the other always dark. If the 
earth, then, had no daily rotatory motion on its axis, one 
geographical half of its surface would always be light ; 
day and night could then exist only by the movements 
of the inhabitants of the earth, passing from one to the 
other hemisphere.x Revolving as it does on its axis, each 
diurnal period includes an alternating condition of shine 
and shadow which we call 



20 Chas. W. ITolbrook's Lunar Tellurian. 
Day and Night. 

Illustrate with tlie tellurian : Turn tlie earth globe on 
its axis from west to east, observing a diurnal change. 
WheUj for example, Charleston, S. C, emerges from the 
night-shade, passing under the day-circle, it is sunrise at 
that place ; when the meridian of that place is opposite 
the solar index it is noon ; sunset at the opposite rim of 
the day-circle, etc. 

The day-circle defines the limit, in space, of the illu- 
mined hemisphere, and enables us to understand that 
geographical limits of day and night are not fixed upon 
the earth, but are constantly moving in zones of black 
Cause of and white from east to w^est as the rotation of the earth 

day and 

liioht. conveys its inhabitants from west to east. 

This fact understood we discover that darkness is 
caused by an eclipse of the sun by the earth. An ob- 
server on the earth is conveyed to a position whence the 
sun is invisible on account of the earth's spherical form. 
At the equator the entire diameter of the earth is be- 
tween the sun and a midnight observer, the latter, if he 
wished to look in the direction of the sun would simply 
see the earth at his feet. 

The absolute negation called space or ether becomes 
illumined by a positive chemical force called the solar 
What is rays, which, mechanically reflected and tossed to and fro 
between the earth and its atmosphere, becomes light. 

Light absorbed is lost. The sands of tropical deserts 
possess the craal power, to a remarkable degree, of alter- 
nately absorbing and reflecting light ; the hot noonday 
with its blinding glare being succeeded by a night of 
darkness so intense that moonlight affords little relief ; 
on a cloudy night darkness is absolute. 



ii-ht ? 



Chas. W. Holbrookes Lunar Tellurian. 21 



Possible uniform periods of day and night : Illustrate 
with the tellurian. Remove the day-circle K and the 
globe ; readjust the globe by carefully screwing the pro- 
jecting pole B on the post at S. 

The earth is now mounted on a perpendicular axis. 
Replace the day-circle and rotate the earth, observing Po^^jbiy 
that people the world over would have equal periods of ^^^^ i^ig^i^- 
day and night. 

Rotate the arm, passing the calender index through 
the 12 months of the zodiac. At any time of the year, 
upon any parallel or meridian, day-light would endure 
12 hours, darkness 12 hours. The sun would rise at 6 
every morning, and set at 6: 12 hours later to an ob- 
server at any locality. Now, as a matter of fact, this is 
true only twice a year (except at the equator), at the 
equinoxes, March 21 and September 21. As we well 
know the periods of day and night not only vary in 
length at different seasons on the same meridian, but 
they differ at the same time on different parallels of a 
meridian. 

On Dec. 21st the Dictator of Peru at Lima observes 
that the sun rises at 6. The President of the United 
States, at Washington, also an early riser, gains two 
hours more sleep, rising with the sun at 8. Both these 
rulers dine simultaneously if at noon, and when the 
Dictator at Lima observes his sunset at 6 p. m. the 
President remarks that it is the shortest day of the year, 
and the sunset hour is 4 p. m. 

People entirely ignorant of natural causes have ob- 
served that in this part of the world the day is longest 
in June and shortest in December, while the nights are 
the reverse. 



22 Chas. W. Holbrookes Lunar Tellurian. 



Remove the day-circle, restore the globe to its true 
position, and again adjust the day-circle. 

We know that the longest day must correspond to the 
shortest night, from the fact that the sum of both must 
always be the same, viz., 24 hours, or the period of one 
diurnal rotation of the earth on its axis. We know that 
dantme ^^ the length of day gradually increases from Dec. 21st to 
June 21st when it reaches its greatest limit; it then 
decreases slowly, a few minutes each day, until Dec. 2 1 st. 
Of course the changes of day periods are the reverse of 
those of night. If a resident of Chicago were to visit 
Buenos Ayres he would find the same relative changes, 
with the important exception that the seasons would be 
reversed ; June 21st marking their midwinter height. 
Journeying farther from the equator he w^ould find 
greater degrees of variation as he approached the poles ; 
upon returning to Quito he would notice that day and 
night were equal the year round. 

Illustrate with the tellurian, calendar index at Dec. 
21st: The day circle divides the earth into two distinct 
hemispheres. For every day of 8 hours in our latitudes 
there must be a night of 16 hours. For every day of 8 
hours there must be a day of 16 hours at the same lati- 
tude south of the equator. All days are 12 hours long 
at the equator. 

Rotate the arm, calendar index at March 20th; turn 
the globe on its axis: 

Days have increased in length as the poles approach 
the day-circle until, at this equinox, they divide the 
period of diurnal time equally with the nights. The 
north frigid zone has emerged from its long w^intry 
night, the south frigid zone has retreated from its long 



Equal day 
aiid night. 



Chas. W. Holbrook's Lunar Tellurian. 23 

summer day. Days north of the equator have increased 
in length while south of the equator nights have in- 
creased. It is spring at Chicago, autumn at Buenos 
Ayres. 

Bring the calendar index to June 20th. 

Xow we observe a marked change. If it were possi- 
ble to reach the north pole a strange sight would excite 
the wonder of the explorer. Arriving there on the 
morning of March 18th, day would be heralded by apoiarday. 
luminous sky, but the sun would not rise ; creeping 
slowly around the horizon, approaching nearer and nearer 
its edge, until March 21st, when its small disk would 
show itself continuously above, still creeping round and 
round daily in spiral circles, until June 20th. On that 
day the sun would describe a circling course 23-^° above 
the horizon. The explorer would seem to stand still, no 
points of compass to guide him, all meridians converg- 
ing under his feet. All changes, variations, and possible 
alternations of day and night and time would have no 
significance to this amazed admirer of perpetual day. 

Pass the calendar index slowly to Sept. 21st. 

In consequence of this motion of the earth in its orbit 
one-half the area of the north frigid zone is removed 
from the sun's light. The explorer now observes that 
the sun, having slowly retraced its diurnal course in 
winding spirals down to the horizon, disappears for a 
long absence of 6 months. 

But to an observer at the south pole on the morning 
of Sept. 2 2d, the sun vv'ould appear above the horizon in 
exactly the same manner as at the north pole 6 months 
previously. 

From June 20th to Sept. 21st day decreases over the J^^^^^j^^^ ^^ 



24 Chas. W. Holbrook's Lunar Tellurian. 

northern hemisphere and must, therefore, increase over 
the southern, while nights are in inverse order, until, at 
this autumnal equinox, as at the vernal equinox, day 
and night are equal. 

Coming to our point of departure Dec. 21st, we find, 
Increase of upon our arrival at the winter solstice, that the entire 

night time. ..,, ,, . r»iTi 

arctic Circle has passed beyond the limits of solar light, 
and for a few days there is no sunrise upon that parallel. 

We have studied the four cardinal positions of our 
earth in its relation to the sun, viz., the position of the 
solstices and the equinoxes, about June 21st and Dec. 
21st, March 21st and Sept. 21st, respectively. 

We now learn why the tropics and polar circles are 
distinguished from the other parallels upon the earth's 
surface : for the former are the farthest parallels from 
the equator, which are illuminated by a vertical sun dur- 
ing the year ; and the latter are the farthest parallels 
from the poles, which pass wholly out of, or wholly into, 
the sun's light. 
Variation of When a parallel lies partly in the illuminated hemi- 

day and ^ . 

night on dif- sphere and partly in the unilluminated, or is divided by 

ferentparal- J- -t- »/ _ ' v^ 

leis at one the day-circle, it has a day and a ni^ht every 24 hours, 

time. •: ' -..Pii . . 

or during every revolution of the earth upon its axis. 
When it lies wholly in one of these hemispheres, its day 
or its night continues until it is again divided by the 
day-circle. Now, as we have seen, parallels of the frigid 
zones are the only parallels, which, at certain times in 
the course of a year, are divided, and at other times 
are not divided, by the day-circle. These parallels are, 
therefore, subject to a greater variety of day and night, 
as regards length, than occurs within the temperate and 
torrid zones. They have, indeed, four distinctly marked 



Chas. W. Holbrook's Lunar Tellurian. 25 

periods during the year ; these periods varying in length 
according to the distance of the given parallel from the 
pole. 

Naming these periods in the most convenient way, 
they are, 1st, a period of continuous day, during which 
the parallel is wholly in the illuminated hemisphere ; 
2dly a period of alternate day and night, during which 
the parallel is partly in the illuminated and partly in the 
unilluminated hemisphere ; 3dly, a period of continuous 
night, during which the parallel is wholly in the unil- 
luminated hemisphere ; and 4thly, a second period of 
alternate day and night, during which the parallel is 
again partly in the illuminated and partly in the unil- 
luminated hemisphere. 

The middle of a period of continuous day, for either 
the- northern or the southern hemisphere, is at the sum- 
mer solstice for the corresponding hemisphere. The mid- 
dle of the succeeding period of alternate day and night 
is at the autumnal equinox. The middle of a period of 
continuous night is at the winter solstice. The middle 
of the succeeding period of alternate day and night is 
at the vernal equinox. 

As an instance of this variety of day and night within 
the frigid zones, let us see how it is exhibited at Spitz- 
bergen during the year. Day gradually increases in 
length, from a momentary glimpse of the sun on Feb. 
21st to 12 hours on March 21st; then to 24 on April 
21st, when it remains continuous until Aug. 21st; it 
then alternates with night, decreasing from 24 hours to 
12 on Sept. 21st, and to a parting glimpse of the sun on 
Oct. 21st; when a continuous night of four months 
succeeds. 



26 Chas. W. Holbrook's Lunar Tellurian. 

Farther .south, as in the southern part of Nova Zem- 
bla, we should find a continuous day and night of about 
six weeks each, and periods of alternate day and night of 
twenty weeks each. Farther north, on the contrary, we 
should find that the periods of alternate day and night 
are shorter, until, at the poles, they cease altogether, and 
the two periods of continuous day and of continuous 
night, each 6 months in length, compose the year. 

The greatest length of day within the torrid zone is 
about 13^ hours, this length occurring upon either tropic. 
The greatest length of day within the tempei^ate zones 
obtains upon the polar circle, where it is 24 houre. The 
length of any given day subtracted from 24 hours gives 
the length of the night, and rice versa. 

Owing to the variable rate at which the sun moves 
betw^een the tropics, the relative length of day and night, 
at the same j)lace^ also changes at a valuable rate. Thus 
this change proceeds the slowest at the times of the 
solstices, and the fastest at the times of the equinoxes. 
The reason of this is to be found in the varying inclina- 
tion of the sun's motion along the ecliptic to the equator. 
Thus, for some time before and after the solstices, the 
sun is describing an arc of the ecliptic (40 or 50 degrees 
in length) which is nearly parallel to the equator on both 
sides of the solstitial points ; consequently the change 
in the sun's declination during this period is very small. 
Variation of During this period, therefore, the sun describes diur- 

night at the nal circles which nearly coincide, and the length of day 
same place. '' 

is nearly constant. On the other hand, about the time 

of the equinoxes, the sun's course has the greatest incli- 
nation to the equator ; and, therefore, the change in the 
length of day is most rapid. The following is an esti- 



Chas. W. Holbrookes Lunar Tellurian. 27 

mate of the rate at which its declination increases from 
the time of the vernal equinox. 

From March 21st to April 21st the sun moves north- 
ward about 10°; from April 21st to May 21st about 9°; 
from May 21st to June 21st about 4°. The same cause 
also affects to the same extent, the rate at which the sun 
moves to and from the zenith between successive noon- 
days, and also determines the rate at which it advances 
along the horizon between successive sunrises and sun- 
sets. It follows, from the equality in the rate at which 
the sun is changing in declination at dates equally re- 
moved from either solstice, that the earth's surface is 
illuminated precisely in the same manner on any pair of 
such days. 

Hence, for everyday in the year except those two ^^PJJ^^^ ^^^^^^^^^ 
which date at the solstice, or the lon2:est and shortest f.^^^ "^^^^ 

' ^ time. 

days, there corresponds another day of the year equal to 
it in length ; also, at dates equally distant from either 
equinox, the sum of the length of these two days or of 
the two nights, must equal 24 hours. Every place upon 
the earth's surface has six months day and six months §'^ months 

•^ day and 

night during the year. At the poles, as we have seen, ^ight. 
the year is divided into a day and night of six months 
each ; at the equator every 24 hours is divided equally 
into a day and night. At places between these two 
positions the sum total of the length of day and night is 
known from this fact, viz., for every day shorter than 12 
hours, during the year, there corresponds one as much 
longer ; and the same is true of night, making the aver- 
age length of each 12 hours for the year ; in which time 
the total length of each must sum up to 6 months, as at 
the equator. 



28 Chas. W. Holbrookes Lunar Tellurian. 

The varied changes in the length of day and night 
may be also studied to advantage by examining the diur- 
nal course of the sun with reference to the horizon of a 
place during the year. 

The daily motion of the earth upon its axis from west 
to east causes an apparent motion of the sun across the 
sky from east to west. Now^ it is evident that the 
apparent motion must be at the same rate as the real ; 
that is, the sun moves both above and below the horizon 
at the rate of 15° every hour, or 1° every 4 minutes. 
The motion is performed in a great circle (viz., the celes- 
tial equator) when the sun is vertical at the equator, or 
upon March 21st and Sept, 21st ; at all other times, the 
diurnal circles described by the sun are small circles. 
An observer at the north pole upon March 21st or Sept, 
21st would be able to follow the sun's course completely 
round the celestial equator, which, at the pole, coincides 
Polar with the horizon (see Fig. 7). In fact, at the pole, the 

sun is rising upon the former date, and setting upon the 
latter. If he continued to observe this course for three 
months subsequently to March 21st, he would find that 
the diurnal circles described by the sun gradually de- 
creased in size, just as parallels decrease from the equa- 
tor to the tropics. The sun's diurnal course is not, how- 
ever, an exact circle ; since, while describing this course, 
it is changing in declination ; it follows, in fact, the 
direction of a spiral. 

The sun ascends about 10° above a polar horizon dur- 
ing the first month of the long polar day, 9° during the 
second, and 4° during the third ; attaining a final dis- 
tance of 23^° above it, after which it descends at a cc^* 
responding rate. 



sunrise. 



Chas. W. Holbrook's Lunar Tellurian. 29 



This motion of the sun from and to the horizon is 
identical with its change in northern declination. 

Description of the Sun. 

Tlie sun differs utterly from the other stars of our 
solar system. It is like none, and none can be com- 
pared to it. In physical and astronomical attributes it is 
peerless. Neither planets, satellites, asteroids, nor com- The peerless 

. . . sun. 

ets can approach it in importance. Its immense size, 
physical constitution, incomparable chemical properties, 
and eternal durance warrant its assignment to sovereign 
and isolated rank. Large enough to furnish a home for 
all the heavenly bodies that revolve around it ; six hun- 
dred times greater than all the planets of its system 
with their satellites and asteroids ; it is one million 
three hundred thousand times larger than our earth. 
The circumnavigation of the earth requires three years ; 
to sail around the sun would take 300 years. That vast -^ bail of 

•^ tire. 

solar globe is a molten mass, emitting perpetual fires ; a 
peculiarity not shared by any other member of our stel- 
lar world ; on the contrary, they are neither hot nor 
luminous of themselves, and if the sun were not, they 
would be plunged into eternal darkness, doomed to ever- 
lastmg cold. 

The light and heat of the sun are changeless, never 
losing their power. The sun is a fixed center of a group 
of stars revolving in their orbits around it at various Oi'bits. 
distances. These planets have their moons which re- 
volve around them as they perform their orbital relation 
to the sun. This fact seems to be the fundamental mys- 
tery of creation. We hastily imagine we know why it 
is so since Newton's discovery of the law of attraction, 



30 Chas. W. Holbrook's Lunar Tellurian. 



but we mistake a word for a thing. Newton was careful 
to say that he proposed a name for a phenomenon wliolly 

Attraction, inexplicable in itself, and of which we know only the 
external manifestation ; that is to say the mathematical 
law. 

We know that bodies approach each other in the ratio 
of their masses, and in inverse ratio of the square of 
their distances ; but wliy they do so we do not know 
and probably never shall during our terrestrial existence. 
It is the cherished hope of the devout astronomer that a 
future and higher state of being may enable him to 
know all mysteries of creation as they are known to 
their Creator, As it is we know only the outward signs 

A universal of that universal agency which binds worlds in correla- 
tive ties ; which holds and controls not merely physical 
masses, but manifests itself throughout the entire do- 
main of Nature, permeating and dominating all life ; 
uniting states, races, classes, interests. 

Newton called it *• attraction," superseding the word 
^^ vortex" of Descartes; Kepler used the terms "elec- 
trization," "affection," "sympathy," "obedience." These 
terms simply describe a force without describing its ori- 
gin. Obedient to this irresistible force the earth re- 
volves around the sun, blessed with its beneficent floods 
of light and heat : from these twin forces we get our 
climates, seasons, days, and nights. 

Vertical and Oblique Rays- 
Heat radiated by the sun is absorbed by the earth 
during day and radiated during night : hence it follows 
that, other things being equal, a 12 hours night would 
radiate the heat absorbed in a 12 hours day. Heat 



Chas. W. Holbrook's Lunar Tellurian. 31 

radiated by the earth at night is not lost in indefinite 
space on account of the atmosphere which surrounds 
the earth, serving it in the capacity of a hot house, 
retaining and distributing solar Hght and heat. It is 
obvious that a minute planet floating in ether at an 
incalculable distance from the sun, would not retain by 
absorption an appreciable amount of heat but for the 
affencv of this spherical shell of atmosphere which is Earth's 

. 1 T 1 • T ^^ ^' atmosphere. 

not peculiar to our globe alone, but is the palladium of 
all planets. 

It is obvious, also, that the spherical earth receives 
most heat upon that portion of its surface v\^hose plane 
is nearly rectangular to the direction of the heat rays, 
viz., the torrid zone. Geographical zones derive their ^Tiy the 

map is di- 

significance from the facts relating to the sun's declina- vided into 

, zones. 

tion' Tropical temperatures are constantly at a high 
degree, owing to vertical rays ; while our temperate 
zones are so named because at those latitudes oblique 
rays impinge upon the convex, are repulsed and scat- 
tered. The atmosphere takes them up and by gradual 
diffusion creates an average for a belt whose extremes 
are far apart. The divisions of zones are arbitrary and 
relate to the sun's declination rather than to tempera- 
tures, and such a mathematical arrangement would not 
exist but for the earth's inclined axis. As has been 
shown in a previous paper, if the axis were perpendicu- 
lar to the ecliptic the duration of light would be uniform 
to all parallels from pole to pole. Heat under the same 
axial conditions would be absorbed and retained by the 
earth's crust with uniform intensity on a parallel the 
year round, varying in ratio of distance from equa- 



82 Chas. W. Holbrook's Lunar Tellurian. 



Milton's 
Augels. 



Climate of 
Mercury. 



Fourier's 
notion. 



torial central rays. These facts bring us to one of the 
most interesting and puzzling of natural phenomena, viz.: 

The Inclination of the Axis. 

Milton says in ''Paradise Lost" that, before our first 
parents sinned, perpetual spring reigned on earth ; but 
that as soon as Adam and Eve had eaten the forbidden 
fruit, angels with flaming swords were dispatched from 
heaven to bend the poles of the earth more than 20°. 
It is fortunate for us that the angelic power stopped at 
23^°j or else our season would have been still more 
abrupt in change. In Mercury the inclination is pro- 
digious — not less than 70°. This planet leans on itself 
as if about to fall. The Mercurian climates would be 
unendurable to us, but a moment's reflection assures us 
that the Creator of worlds can enact His Divine will 
upon all his works, and that the dwellers in each planet- 
ary home are adapted to their environment, otherwise 
they could not exist. 

Fourier declared it to be possible for man to exert a 
power sufiicient to readjust the earth on an axis perpen- 
dicular to the plane of its annual orbit, and to restore 
the equality of the seasons. He neglected to mention 
one important point, viz., the mechanical process by 
which this power could be exercised. His theory re- 
sembles the act of a drowning man who thought to save 
himself, by seizing his own hair ; and that other theorist 
who had his suspenders made very strong, that he might 
by a shrug of the shoulders, lift himself over wet places. 

The axis of Yenus is inclined 75°. Babinet describes 
as follows the effect of their great inclination on seasons : 

^'The planet which certainly presents the most re- 



CiiAS. W. Holbrook's Lunar Tellurian. 33 

-' markable climatoloa:ical peculiarities is Venus, which in p/'ii^inet ou 

' bulk and distance from the sun is almost the exact 

'counterpart of the earth. She turns very obliquely 

' on herself. If we take the earth for a point of com- 

' parison, the sun m summer comes almost above Cuba. 

'The obliquity of Venus is so great that in summer 

' the sun attains latitudes higher than those of Belgium. 

' It follows from this that the two poles, subjected in 

' turn to an almost vertical sun, which never sets (and 

' this at intervals of four months, since the year is but 

•eight months long), do not permit snow and ice to 

' accumulate. This planet has no temperate zone ; 

' the torrid and frigid zones encroach upon each other 

'and rule successively over the regions which in our 

'world constitute the temperate zone. Hence results 

' constant conflict of the elements agreeably to what our 

• observation has taught us as to the difficulty of seeing 

'the continents of Venus across the veil of her atmos- 

'phere, incessantly disturbed by the rapid variation of 

' the height of the sun, of the duration of days, and the 

' transports of air and moisture that render the solar rays 

'twice as powerful as those that come to the earth." 

Reasoning from the analogy of the conditions of our 
earthly life, Jupiter would seem to be a very desirable 
place of residence for those discontented souls who long 
for what thev cannot have. The axis of Jupiter is in- Jupiter's 

" ^ climate. 

clined but slightly, hence it has, like Saturn, a kind of 
perennial spring, that is to say, a reception of solar light 
and heat operating in equal proportions along the same 
parallels. With short days and nights of five hours 
each, its year is equal to twelve of ours. Owing to great 
distance from the sun, days can be but faintly illumined. 
3 



3-4 Chas. W. Holbrook's Lunar Tellurian. 

Astronomers there must be enabled to see the most beau- 
tiful stars at midday. In compensation for short nights 
Jupiter has near about him four moons which supply a 
steady light ; his twilights are long, hence the light of 
his day and night must be nearly equal. Perfect equali- 
ty of days and nights and of seasons on all his parallels; 
so that the discontented Jovian needs but to change his 
latitude to find a season befitting his various require- 
ments, desires, and whims. 
Results of The inclination of the axis of a planet is the test of its 

inclined ^ ^ ^ 

axis. condition as an abode of life in any form. In the study 

of our subjects concerning light and heat the inclination 
of the earth's axis is easily seen to be the cause of all 
variations of duration and degree in our reception of 
these two primal elements of life. We have observed 
that during an orbital revolution of the earth around the 
sun in a year, the poles vary in their angular relation to 
vertical rays, though always pointing in the same direc- 

Paraiieiism tion — toward the north star. This is called the ^'paral- 

of the poles. 

lelism of the poles." This is a mystery to most pupils, 
for they are apt to wonder why we do not call the axis 
perpendicular and every thing else inclined. In their 
minds it is a mere matter of names, and if you try to 
explain by saying that the axis is inclined to the plane 
of the earth's orbit, they are worse off than ever ; for 
you have but added more names: and names are nothing 
without an understanding of the thiiig which is back of 
the name. Object lessons assist the imagination, making 
it not only active but constructive. 

If you have made them familiar with the few simple 
natural facts of daily observations as herein described, 
such as these — that the sun is at rest and the earth 



Chas. W. Holbrook's Lunar Tellurian. 35 

moves; that heat may be received alike at different in- 
clinations, but 7}ot retained where the rays fall obliquely; 
that heat absorbed during the day is lost by radiation 
during the night, you have laid a foundation for some 
beautiful illustrations. When you tell them that the 
earth's axis is inclined^ if they are bright they ask — 

^' Inchned to what f " 

'• The Plane of the Ecliptic ! " 

''What is that?" 

If you are not familiar with the theory of the eclip- P^^e of the 

•^ . . "^ . -^ ecliptic. 

tic, do not say anything about it until you are; it is 
worse than Greek roots and French verbs on a slight 
acquaintance. Turn the earth or globe on its axis and 
observe that there is a line which crosses the equator at 
the prime meridian, runs southward to the Tropic of 
Capricorn, upward across equator again to Cancer. The 
equator and parallels are always visible while the globe 
is revolving, but this line wobbles about in a zig-zag 
manner, and is invisble if the globe moves rapidly. 
Bring this erratic line to a horizontal level and it is in 
line w^ith the solar index E and J. The index and the 
line now represent the Plane of the Ecliptic, or an im- 
aginary line drawn from the sun's to the earth's centers. 

Such a line would always touch the earth's surface, as The Plane 

•^ illustrated. 

the solar index might, somewhere in the tropics, and 
to that fact is due the division, by the early astron- 
omers, of the earth's surface into geographical zones. 
Rotate the arm and explain that the solar index points 
at the ecliptic But this explains only the geograph- 
ical ecliptic marked on the map for convenience. 
Rotate the arm entirely round the sun and explain that 
the ecliptic is the level of the earth's orbit. Are you 



36 Chas. W. Holbrook's Lunar Tellurian. 

not as far from the real fact as ever ? For if you turn 
the globe on its axis in the slightest degree, your line of 
the ecliptic goes off its balance ! 

Bend the upper half of the day circle K down to a 
level with J, and rotate the arm backward and forward. 
You can by this means describe the fact that the true 
ecliptic exists outside and away from the earth's sur- 
face, and you have gained a point. This experiment 
proves that the Plane of the Ecliptic is parallel to or 
level with the earth's orbit. 

Tip up the tellurian and rotate the arm. The effect is 
the same. 

If your pupils whirl on their toes, without moving 
out of their tracks, they will describe the earth's daily 
rotation on its axis. If they run around a post they 
describe an orbit. If they both whirl and run they 
describe both motions of the earth in a year. 

If you stand in the center of a circle of pupils and 
pass a cord from one to another, around the circle, 
holding the end yourself, the cord will, if level, illus- 
trate the Plane of the Ecliptic. You are the sun, one- 
half above, one-half below, the plane. Each of the 
pupils illustrates the earth in one of its positions. The 
whole circle is the orbit. Take a blackboard pointer 
and explain as you pass its farther end round the circle, 
that the earth always moves on that level; then raise 
and lower your stick as you describe the moon's orbit 
once a month round the earth, one-half the time above 
the ecliptic, the other half below it. 
Heights A house upon a mountain top is thirty feet hi2:h. 

from sea ^ '- \ . 

level. High above what ? The mountain. How high is the 

mountain ? Well, the surveyors were around a year or 



Chas. W. Holbrook's Lunar Tellurian. 37 



two ago and they said the top of the mountain was 2,000 
feet above the valley where the water of the river is 
made level by. a dam. But how high is the dam ? The 
surveyors said that there were ten feet fall between the 
reservoir and the factories below. How high are the 
factories? 40 feet from the river where the water is 
returned to its natural channel. How high is the river 
at the factories? 50 feet above the sea level. Now 
we have reached our destination! The mountain, then, 
is 2,100 feet above sea level. 

The early surveyors of the skies found a level f or ^stronomi- 

•^ '^ cal level. 

their base line. It is the Plane of the Ecliptic — the path 
in which the earth always moves in its annual pilgrim- 
age round the sun. Describe a circle on the black- 
board, one foot in diameter. A few feet distant de- 
scribe one a trifle smaller. Draw a horizontal mark 
through the middle of both, a continuous line. The 
larger circle is the sun, the smaller the earth. The 
line is the ecliptic. Erase the earth and describe it the 
other side of the sun. It has passed from winter to 
summer but it has not left the line. Describe the same 
by rotating the arm. The earth does not jump up and 
out of the Plane of the Ecliptic as the moon likes to do; 
as a flying fish might dart up and out of the sea, then 
back again to the depths below the sea level. Our re- 
spectable and dignified planet moves forever along the 
same level, one-half above, the other half below, very 
much as the hull of a large ocean steamship moves over 
water, one-half submerged. The theory of the ecliptic 
once made plain, we pass on to an acquaintance with the 
Zodiac. 

The ancient astronomers discovered that the sun 



38 Chas. W. Holbrook's Lunar Tellurian. 

appeared to have passed among certain groups of fixed 
stars. To these groups they gave the names now used, 
zodiac^^ *^^ These constellations occupy space in a belt of the 
heavens parallel to the plane of the ecliptic and extend- 
ing 8 degrees above and below it. "Within the limits of 
this Zodiacal Belt all the principal planets of our solar 
system have their orbits. But the earth is the only one 
that sticks to the dead level of the plane itself. They 
divided the belt into 12 portions of space to which they 
gave the Signs of the Zodiac. 

Retaining this arrangement, modern astronomers say 
that on March 20th the sun enters the first point of 
Aries. Illustrate by bringing the solar index to March 
20th. Thus, while the sun is in one sign, the earth, as 
seen from the sun, is in the opposite one. 
■ Rotate the arm and observe that the earth is above 
one sign when the sun is over a sign on the opposite 
side of the circle. Illustrate better by allowing the 
pupil to stand on the night side of the globe. Elevate 
the solar index to the top of post D and ask them to 
squint along the direction of the solar index to a dis- 
tant window. Rotate the arm a little and they may 
change their positions and discover another window, 
etc. Call one window Leo, and let them pass around to 
the day side and look in the opposite direction. The 
earth is in Aquarius, where the sun will be in six 
months. Rotate the arm to prove it. 

You can, if you choose, easily construct a good Zo- 
diacal Belt; take strips of pasteboard a few inches wide 
and by fastening the ends together, make a circle four 
feet in diameter. Divide the inner surface into 12 
parts and name them. Make a distinct mark through 



Chas. W. Holbrook's Lunar Tellurian. 39 

the middle of your belt, entirely around. Now arrange 
your circle on a level at the right height and place the 
tellurian in the center of it. If you have been careful, 
the solar index,- restored to its proper place on the post, 
will point constantly at the dividing line on your belt, 
as you rotate the arm. That line is our old friend the 
Plane of the Ecliptic, and the 12 spaces are the Signs of 
the Zodiac. 

*' The Ram and Bull lead off the line; 
Next Twins, and Crab, and Lion shines; 

The Virgin and the Scales. 
Scorpio and Archer next are due, 
The Goat and Water-bearer too; 

And Fish with glittering scales." 

The appearance of the sun and moon in these signs 
at regular intervals of years and months proved to the 
early observers that the sun described an orbit around 
the earth, or else the earth had an orbit around the sun ; 
whichever it might be, there was a level — the Plane of 
the Ecliptic. * 

Having found a base, we know that the earth is 
inclined to that level because of the variation in the 
sun's apparent altitude. 

Zenith is a point of the farthest extremity of a line Zenith, 
extending from the center of the earth, through its 
crust, into space ; the zenith of any observer is directly 
overhead as he stands erect and looks upward. 

Rectify the globe for Dec. 21st. 

The solar index E points at the Tropic of Capricorn; 
a resident of one of the Gambler Islands sees the sun in 
his zenith at noon, Dec. 21st. 

Rotate to March 20th. 



40 Chas. W. Holbrook's Lunar Tellurian. 

A resident of Quito sees the sun in his zenith. Ro- 
tate to June 20th. The sun is in zenith, or exactly 
overhead at Havana, and appears nearly in the zenith 
as far north as Boston; but in fact is 20 degrees south 
of zenith; its great distance lessening the angle of rays 
to an observer on the 45th parallel. When the sun is 
Sw^Bun^ in zenith at Gambler Islands, its vertical rays fall upon 
a zone north and south, 45 degrees in width. To us 
above the 40th parallel, the sun, Dec. 21st, appears far 
south at noon, while on June 20th it appears nearly 
overhead. Between these extremes of low and high sun 
is the apparent variation, of sun's altitude. 

You may hear people remark in February that winter 
cannot last much longer because the sun is '^ high." 

In the autumn we are warned of approaching winter 

by a ''low sun." When the sun is in Capricornus it is 

"low," but rises higher every day until it is in Cancer. 

High and You will find in the almanacs little crescent-moons with 

low moon. 

the horns pointing upward or downward, signifying 
that the moon runs '' high or low." Rotate the arm 
entirely round the sun, observing that a person must, if 
he wishes to keep the noon sun in his zenith, travel 
north from Cobija, South America. 

When should he start? About January 10th. At 
what season ? Our midwinter and his midsummer. 

Why not start Dec. 21st ? 

Let us see; rectify for Dec. 21st. 

This is called the Winter Solstice, because the sun 
stands at the same altitude at noon for nearly a month. 

Turn the arm backward until the Cardinal index 
covers Nov. lOth. Observe that the ecliptic line has 
nearly reached the Tropic of Capricorn. Owing to its 



Chas. W. Holbrookes Luxar Tellurian. 41 

distance the sun's altitude at noon would appear to be 
zenith at Gambier Islands and it would rise and set in 
the same place for nearlv a month. Our Gambier a lover of 

■^ " . vertical 

Islander would travel almost exactly eastward, during rays, 
that time, starting early in November. He must needs 
sail 4,000 miles in 60 days. Describe his slov/ journey 
under the solar index by slowly bringing the calendar 
index to Dec. 20th. We would read in the paper that 
while he was melting under the vertical rays of mid- 
summer sun we were burning our income in coal to keep 
from freezing under the oblique rays which fall upon 
our northern regions in midwinter. To make matters 
worse, we would notice that the improvement in the 
angles was very slight, for the sun, to the northern ob- 
server, rises, culminates, and sets in the same little arc 
day after day, until January. An observer at the Arc- 
tic Circle would see the sun barely above his southern 
horizon at noon, for many days prior to Dec. 2 1 st. On 
that day the sun merely peeps over it and drops back 
out of sight Old Sol sends his regrets to the Esqui- old Soi's 

, T , ^^ , ^ ^ . bad habits. 

mau. pleadmg other engagements. He is bound to give 
our traveler a good hot noon, and has promised to stay 
up all night with some friends at the Antarctic Circle. 

By Jan. 10th, the tropical traveler lands on the west- 
ern coast of northern Chili, and sleeps at Cobija. 

Every 24 hours he has sailed eastward 67 miles, 
reckoning from his horizon. Each day his sunrise, 
noon, and sunset have been described by the opparent 
motion of the sun through an arc extending from east 
to west, through zenith. And his latitude has changed 
but few degrees, because his journey up to this point 
has been along a route where the noon sun is nearly at 
the same altitude. 



42 Chas. W. Holbrook's Lunar Tellurian. 

His days have been about fourteen hours, his nights 
Our tropical ten hours Ions;. At Cobiia he finds his watch does not 

traveler. ^ . . . '^ 

agree with meridian time. He has journeyed eastward 
4,000 miles in sixty days, leaving home November 10th, 
1885, arriving at Cobija as he supposed at 10 p.m. Jan- 
uary 9, 1886, but upon correcting his watch he finds 
it to be January 10th, 2 a.m. 

He has kept his diary every day and noted the fact 
that the sun rose earlier each day, and set earlier, but 
he has gained four hours by traveling toward sunrise. 
The captain of the ship bids him good-bye at Cobija, re- 
marking that he will not change his w^atch as the four 
hours will be restored by the time he reaches home, 
sailing westward. 

At sunrise, Jan, 1 0th, our friend telegraphs an acquaint- 
ance in London that he shall continue his experiments 
with vertical rays, therefore he shall travel northward to 
Quito. It takes six hours to get the dispatch to London, 
and as the sun rose at 6 at Cobija, should it not be 12 in 
London when, the dispatch is received ? Bring the Car- 
dinal index to Jan. 10th. Eotate the globe until Cobija 
is at the western edge of the day circle. 

Point the polar index to 6; rotate the globe slowly 
until Cobija is under the solar index. 

AY here is London ? 

Arriving at Quito March 20th, his watch tells him that 
it is noon, but it is nearly sunset in fact. He has lost 
over five hours by pursuing a northward course 1,400 
miles. The journey of the tropical traveler reveals a 
few natural facts: 
Hisdiscove- i^ Variation of time. 

2. Variation of area of Vertical Rays. 

3. Variable Reception of light and heat. 



nes 



Chas. W. Holbrook's Lunar Tellurian. 43 

These phenomena are caused by the double motion of 
the earth; viz.: a daily rotation around its own axis, a 
yearly rotation around the sun, both motions being ac- 
complished with one-half of the earth heated and illumin- 
ated by the sun. 

To find where Vertical rays visit. 

Rectify the tellurian for Dec. 21st. Bring the calen- 
dar index over the month or day designated. Rotate the 
earth and the solar index will cover the area of vertical 
rays. Practically, the area extends 23 1 degrees in any 
direction from the point covered by the solar index. 

Examples- 

What countries receive vertical rays in Feb., May, 
Aug., Nov. ? 

Upon what parallels do vertical rays fall in June ? 

There can be no such a thing as unequal distribution The tireless 
of light and heat, for, as has been remarked before, the 
sun constantly, invariably distributes both impartially. 
AYe have seen that if our globe, the earth, were mounted 
on a perpendicular axis, all portions of its surface would 
receive light and, relatively to latitude, heat equally. 
Day and night would be equally divided the world over. 

Rectify the tellurian for Dec. 21st, and rotate the 
globe, observing that while one-half of the earth receives 
the light of the sun, the opposite half does not. Rotate 
the arm to June 20th. The earth continues to receive 
the same amount of light and heat, but, by its changed 
position, the Arctic region is now brought into the 
light. 

An observer upon a parallel would see the sun in its 
apparent course through the sky describe an arc of the 



44 Chas. W. FTolbrook's Lunar Tellurian. 

same degree of curvature as the parallel upon the globe. 
We find that the Tece]Dtion by the earth of light and heat 
varies according to the earth's position in relation to the 
sun. 

Observe that the southern hemisphere is projected into 
constant day. 

V7hat is the duration of light at the Antarctic Circle ? 
24 hours. 

At Cobija, South America ? 

Bring Cobija to the point of sunrise and set the polar 
index to 12. 
Examples. Rotate the globe on its axis and you find that when 
Cobija touches the point of sunset the index marks 2 + 
12 Z3 14 hours. Divide by 2 and you get 7 hours a. m. 
and 7 hours p. m. Their sunrise must therefore occur at 
12 — 7 =r 5 o clock. Their sunset at 7 o'clock. 

Bring Quito to sunrise and proceed as before. The 
index gives a 12 -hours day. Try Cape Sable, Florida; 
you find a day of 10 hours — sunrise at 7, sunset at 5. 
Try San Francisco: nine hours of light and 15 hours of 
night. 

Try Vancouver's Island: *1^ hours of daylight and 16^ 
of night. 

Try the North Pole ! 

Continue these experiments, observing that, at the 
Solstices in Dec. and June, light and heat^ though equally 
distributed by the sun, are variably received by the 
earth. A northern winter is offset by a southern sum- 
mer and vice versa. At the equinoxes, March 20th and 
September 23d, heat and light are equally received on 
all portions of the earth's surface. 



Chas. W. Holbrook's Lunar Tellurian. 45 

A Few Convenient Rules- 
Given the length of day, subtract from 24 to find Rules, 
length of night; divide the hours of night by 2 to find 
sunrise; divide the hours of day by 2 to find sunset. 

Given the hour of sunset, subtract from 12 to find 
sunrise. 

Double the time of sunrise to find length of night. 
Double the time of sunset to find length of day. 

Twilight. 

The daily mornino- and evenins; 2:low, before sunrise cause of 

J o & & .' twilight. 

and after sunset, would not exist but for the gaseous 
envelope which surrounds the earth. Atmosphere is 
about 50 miles thick, catching the tangential rays of 
rising and setting sun, bending them downward toward 
the earth by refraction, and diffusing them by reflection. 
Without the aid of atmosphere solar hght, striking the 
earth's surface, would be reflected and instantly lost in 
etheric space; in such a manner that, though to an 
observer on another planet the earth would look bright, 
the observer on the earth would gaze off into deep dark- 
ness even at midday; the sun appearing to resemble a 
full moon. No mornin^; twilio-ht would herald the sun's Absence of 

-. ? , , . -, twilight. 

approach: no evening graduation would warn us ot the 
coming night; but abrupt changes from one extreme to 
the other would be our lot. If bv some astronomical i^^^^^^PJion 

of all life on 

calamity, the atmosphere should suddenly cease to exist, the earth, 
sound would terminate in silence, respiration become 
impossible, the frigid cold of space would seal the earth's 
crust in eternal frosts, rivers, lakes, and seas be swallowed 
up by universal absorption; the planet on which we 



46 Chas. W. IIolbrook's Lunar Tellurian. 



Extent of 
twilight. 



Shortest 
twilight. 



dwell would become, in one brief moment, a voiceless, 
lifeless orb. 

We have observed that one half the earth is always 
bathed in light; between the two hemispheres of day and 
night exists a narrow belt encircling the earth, about 18° 
wide, called twilight The width of this belt is, theoretic- 
ally, 18°, but this measurement denotes an average rather 
than a uniform rate. Twilight is increased by cold and 
decreased by heat; its duration also depends a good deal 
upon locality, varying 5° from equator to poles. The 
time required for the sunrise line to travel 18° depends 
not only upon the angle between the circle of declination 
which the sun is describing, and a given horizon, but 
also upon the size of this circle of declination. The only 
horizons for which the entire diurnal course of sunrise is 
at any time coincident with a vertical circle are the hori- 
zons of places upon the equator at the times of the 
equinoxes; the shortest twilight, therefore, is seen at the 
equator on March 21st and Sept. 21st, enduring only 1 
hour and 20 minutes. 

The higher the latitude the greater the obliquity of its 
horizon to the sun's course; it is plain, therefore, with 
the aid of the tellurian, why twilight varies from equator 
to pole; simply because an observer at the equator is 
carried, by the earth's motion, through the twilight belt 
with greater speed than he would be at high latitudes. 

Illustrate with the tellurian : 

The space between the day-circle K and the night- 
shade L is the twilight belt. Outside the Arctic and Ant- 
arctic regions there are two twilights each day. Rotate 
the globe and observe the increased obliquity of paral- 
lels, crossing the belt, as you pass from equator to poles. 



Chas. W. Holbrookes Lunar Tellurian. 47 

Bring the calendar index to Dec. 21st : 

The Arctic region at the time of winter solstice, has 
twihght and night for its alternatives ; twilight increas- 
ingly succeeded by dayhght until the time of vernal equi- 
nox, March 21st. At this time daylight and twilight are 
the alternatives — no night. Day now increases upon Aiterna- 
twilight until the time of summer solstice, June 21st, 
when it is all day. Continue the observations around 
to Dec. 21st, not forgetting to notice that the order of 
change and duration at the Antarctic region is the same, 
though in inverse order. 

To find the duration of twilights : 

Bring the given place to the eastern slope of the day- 
circle, if in winter, to the western if in summer, to find 
evening twilights ; set the polar index to 12, and rotate 
the globe until the place is under the edge of the night- 
shade. The index will show the duration of both morn- 
ing and evening twilight. 

To illustrate : Bring Cape Farewell under the day- 
circle Dec. 20th. Index 12. Rotate the earth and find 
a long twihght of 6 hours. 

The Sun's Declination. 

We have used the term ''sun's altitude" to express 
what is apparent from the earth. The sun aj^pears high 
or low according to the season. Astronomers use the 
word '^ declination" to define the position, north and 
south of the equator, upon which the vertical ray, the Prime verti- 
central ray, the maximum degree of heat falls. ^eat. 

When this ray reaches the earth north of the equator, 
the sun is said to have a northern declination; when 
south of the equator, a southern declination. We have 



48 Chas. W. Holbrookes Lunar Tellurian. 

seen that the greatest northern declination is at the 
Tropic of Cancer, June 21st; the greatest southern 
declination is at the Tropic of Capricorn, Dec. 21st; 
March 20th, and Sept. 23d, the sun has no declination. 
Illustrate with the tellurian : 

Bring the calendar index to March 21st. Adjust the 
solar index by sliding up or downward until its point J 
covers the equator. At the times of equinox the sun 
has no declination, its meridian altitude being reckoned 
north and south of that line, which is zero. Rotate the 
globe from west to east, observing that an observer upon 
any parallel of the earth's surface would see the sun 
rise, culminate, and set, describing an arc corresponding 
in degree to that upon which he stands, measured from 
edge to edge of the day-circle. 

Eotate the globe rapidly, bringing the calendar index 

decUnafion ^^^^^7 ^^ June 2 1st. When the globe stops, observe 
that the solar index now covers the Tropic of Cancer, 
and for each day during the intervening period of three 
months the sun has had a circle of declination and me- 
ridian altitude. When the sun is north of the equator, 
northern circles of decHnation have their longer arc 
above the horizon and shorter below it, therefore days 
are longer and nights shorter than 12 hours. 

Increased The ^i^eater the distance from the equator the s-reater 

variation of ^ . 

time at high the difference between the length of the two arcs into 

latitudes. . . ..... , . 

which a circle of declination is divided by the horizon ; 
and, of course, the greater disparity of day and night. 

The more oblique the sphere, or the higher the lati- 
tude of a place the more does its horizon diifer in direc- 
tion from that of the sun's course, hence the longer th^ 
distance measured upon the horizon which corresponds 



Chas. W. IIolbrook's Lunar Tklluiuan. 49 



to a change of a given number of degrees in declina- 
tion. In liio-li latitudes tlie sun rises and sets at a Rapid ad- 

. \aiiceof 

more rapid rate of advance along the horizon, and also points of 

. "" sunrise. 

approaches more nearly to its northern and southern 
points. The horizon whose inclination to the equator is 
23^° has the sun within its northern or southern point 
at the respective times of the solstices ; so that sunrise Sunrise at 

^ the polar 

and sunset must take place within every point of this circles. 
horizon during the year, and one diurnal circle be 
described above it at the summer solstice. This is the 
case at places upon the polar circles, as may be seen 
with the tellurian at June 21st, the arctic circle being 
projected wholly within the day-circle. 

At places within the polar circles the sun rises and 
sets at every point upon their horizons during the year; 
passing along the horizon at a more rapid rate the nearer 
the place is to the pole, and reaching the north or the 
south point i^reviously to the time of a solstice. The time 
previously depends upon the distance of the given place 
from the polar circle, being greater with an increase of 
latitude. As the latitude increases, the greater, there- i^iumai 

^ ' circles near 

fore, must be the number of entire diurnal circles which the poles, 
the sun describes continuously above the horizon during 
the year ; and this agrees also with the increase in the 
continuance of day in this direction. The angle between 
these circles and the horizon diminishes towards the 
poles, until, at the poles, a diiference of direction be- 
tween the two ceases altogether, and the sun moves 
either in the horizon, or in a direction parallel to the 
horizon. 

The rate at which the sun's diurnal circles ascend 
above the horizon, or descend towards it, within the 
4 



50 Chas. W. Holbrook's LUxXar Tellurian. 

polar regions (not now including the poles), depends 
upon the position of the sun within the ecliptic when 
describing them. If the day is two months or less, the 
sun is, during that time, describing an arc of the ecliptic 
nearly parallel to the equator, and moves northward or 
southward, therefore, at its slowest rate. When the 
day is a longer one, the sun leaves and returns to the 
horizon at its most rapid rate, or nearly so, during the 
former and the latter portion of it. 
Sim's ^g ^^ instance of the variety which the sun's diurnal 

course at 

Spitzber- circuits exhibit in the frigid zones, let us follow the 
sun's course at Spitzbergen for a year, beginnmg with 
the dawn succeeding a period of continuous night. 

The sun appears in the southern point of the horizon 
upon Feb. 21st, and immediately sets without an inter- 
Arctic day. yening course. The next day it describes a small arc, 
the next a longer one, and so on, until it rises in the 
east and sets in the west, having moved, both in rising 
and in setting, through a quarter of the horizon in com- 
ing to these equinoctial points. It now^ culminates 10^ 
above the horizon. Subsequently to March 21st it de- 
scribes arcs increasing in length until April 21st, when 
its whole circuit is brought above the horizon, and so 
remains, rising higher and higher, until the time of the 
summer solstice. At this time the sun comes to the 
meridian of Spitzbergen at a distance of 35° above the 
south point of the horizon, and 13° above the north; 
the difference between these numbers (or 22°) showing 
the obliquity of its diurnal circles to the horizon of 
Spitzbergen. After this date the sun begins slowly to 
descend, until it sinks below the northern point of the 
horizon for a moment on August 21st; after which it 



Chas. W. Holbrook's Lunar Tellurian. 51 

describes arcs gradually decreasing in length until it has 
left the visible heavens altogether upon Oct. 21st. 

The zenith, distance of the sun at noon for any given 
place north of the equator is equal to the difference 
between the latitude of the place and the sun's declina- 
tion, if the latter is north declination ; or to their sum, 
if it is south declination. The meridian altitude of the Meridian 

^ 1 1' nc ^ ' ' ^ altitudeS. 

sun IS always equal to the diiierence between its zenith 
distance and 90°. The reason for these rules should be 
found by the learner ; and he should also derive a cor- 
responding rule for places in the southern hemisphere. 
Thus, when vertical at the equator, the sun culminates 
20° from the zenith, or 70° above the horizon, at the 
latitude of 20° N. or S.. towards the southern point of 
the horizon at the former latitude, and northern at the 
latter. When vertical at the Tropic of Capricorn, its 
zenith distance is 23|° at the equator, 33^° upon the 
10th northern parallel, 67-J-° at the south pole, and so on. 

Whenever the sun is vertical at a latitude north of a Sun at noon 

- -i . • ^ -I • north of 

given place, it culminates at a point of the meridian zenith, 
north of the horizon of that place ; whenever it is verti- 
cal at a latitude south of a given place, it culminates 
south of the horizon of that place. It therefore culmi- South of 
nates both upon the north and the south sides of the 
zenith at places within the torrid zones, but only upon 
one side of the zenith at places within either temperate 
zone ; namely, always towards the southern point of the Either side 
horizon north of the Tropic of Cancer and always to- 
wards the northern point of the horizon south of the 
Tropic of Capricorn. Beyond the torrid zone the sun 
culminates at its extreme zenith distances at the time of 
the solstices ; occupying its nearest position to the zenith 



52 Chas. W. Holbrook's Lunar Tellurian. 

at noonday of the summer solstice and its farthest posi- 
tion 'at the winter solstice; June 21st, north of the 
equator ; Dec. 21st, south of the equator. \ 

Change of Seasons- 

Variation The meridian altitude of the sun at a s:iven time 

and change ^ 

of seasons, denotes the season. The difference between vertical and 
oblique rays indicates the difference of seasons. The pro- 
cess of differentiation causes chavge of scaso?is. 

At the equator there is but one season, perpetual sum- 
mer ; though a given locality may have its climate which 
is due to local causes. Away from the equator seasons 
change, even within the tropics, the degree of variation 
always being in ratio of distance from the equator. If 

All climates the earth had no orbital motion, there would be diifer- 

and no , 

seasons. ent climates for different parallels, but no change of 
seasons ; but the orbital motion constantly changes the 
angle of the plane of a parallel circle and the vertical 

Causes of ysljs ; hence we may say change of seasons is caused by 
differing durations of day and night ; or, which is equiva- 
lent, the amount of heat daily absorbed and retained by 
the earth. 

With the tellurian rectified for Dec. 21st, we observe 
that the declination of the sun is at the extreme south- 
ern point. Bearing in mind, that all natural conditions 
are reversed for opposite directions from the equator, 
we will confine our attention to the relations of seasons 
to our northern latitudes. At this time of winter sol- 
stice, the earth is frost-bound. Since Sept. 21st the 
days have decreased and the nights increased in length ; 

a northern i^eat absorbed durino; the summer has been lost by radia- 
tion ; cold has accumulated, and winter reigns. Very 



Chas. W. IIolbrook's Lunar Tellurian. 53 

oblique rays afford but little heat, too little to counter- 
act the long cold nights, and all the veins of vegetable 
growth are sealed, the sinews of the soil paralyzed by 
the icy grasp. 

The average man earns barely enough during the year its hard- 
to keep his family comfortable, for a long winter calls ' 
for increased expenditure for clothing, food, and fuel to 
sustain health. 

Our rio-orous wmtry climate is a terror to the feeble, ^^® advant- 

^ "^ ' ages. 

but to those who have and know how to maintain good 
health this season has its compensations m facilities for 
recreation, repose, study, and meditation. Civilization 
depends in a great degree upon long nights. High 
grades of intellectual attainment are commonly found m 
high latitudes. Nature is silent with sullen impotence, 
save the fierce clatter of hail, blinding blasts of snow, 
and the terrific howls. of the Manitoba blizzard. 

It may be asked why, at March 21st, when day and ^p^^^s- 
night are equal m all places, the average temperature 
is not the same as at Sept. 21st when like conditions 
prevail ? 

The explanation is found in the fact that during a Reasons 

why our 

northern winter the crust of the earth accumulates so climate is 

colder 

much cold that at the vernal equinox the gain in solar March soth 

1 11 1-T T n t t T ' ^haii Sep- 

heat has been lost m the reduction of cold. It requires tember 20th. 
as much heat to melt a sheet of ice one inch thick as 
would suffice to raise the temperature of 800 cubic feet 
of air from zero to 100 One can readily perceive why, 
in our latitudes, the climate is not so warm at vernal 
as it is at autumnal equinox, because at Sept. 21st the 
accumulated heat of the summer has not yet been lost 
by radiation. Therefore, with the axiom that a 12- 



64 Chas. W. Holbrook's Lunar Tellurian. 

hours' night will radiate the heat of a 12-hours' day, we 
learn that where this equality of day and night does not 
exist for any length of time, the climate depends upon 
what the soil has accumulated as well as upon what it is 
daily receiving and dispensing. 

To thoroughly understand the difference in degrees of 
reception and accumulation of heat let us experiment 
further. 

Bring the calendar index to June 21st : 

Summer. The northern hemisphere is projected farther into the 

illumined space, toward the sun, where light and heat 
always prevail. This change of position has come gradu- 
ally since the advent of spring. Days being longer we 
must have received more heat than our nights alone 
would radiate ; what becomes of the surplus ? It is 
absorbed in the process of liquefaction and evaporation. 
The sun thaws or melts snow, frost, and ice into water, 
which evaporates and flows away to the sea. We do 
not experience genuine summer heat until after we have 
passed the period of vertical rays and are well on our 
way to a position of oblique rays. Hence, we accumu- 
late heat during the shorter days which follow the time 
of solstice, June 21st, provided the days are longer than 
12 hours. In July, August, and September we have 
our highest temperature, for then, and not till then, is 
our soil in a condition fit for accumulation of heat. 

Earth^s cen- An important influence which tends to ameliorate the 

tral heat. " ^ 

condition of a cold season is the internal heat of the 
earth. All planets have a temperature of their own, 
independently of the sun. They were originally m a 
liquid state produced by heat, and have become fit for 
organized life by cooling to a solid condition. This 



Chas. W. Holbrookes Lunar Tellurian. 55 

individual heat is still preserved in the center of the 
earth. At any considerable depth below sea level this 
heat becomes perceptible. 

As a result of this brief study of the seasons, we find : 

1. Distribution of heat is always equal. 

2. The sun emits only vertical rays, the obliquity ap- 
pertaining to the angle upon which they fall. 

3. Reception of heat is equal at all times and places 
durmg day, but accumulation of heat depends upon the 
relative preponderance of the day over the duration of 
Its corresponding night. 

4. Vertical rays are positive only at the tropics ; out- 
side that zone they are negative through the process of 
reducing accumulated cold. 

5. Reception and accumulation of heat depend more 
directly upon the relative duration of day and night 
than upon vertical rays. 

Climates. 

The tellurian illustrates, as well as any instrument 
can, the important and interesting phenomena of cli- 
mates, and their relations to seasons. 

Seasons are belts of mean temperature encircling the Difference 

, . nil 11 between 

eartli m zones parallel to the equator ; and the name, seasons and 

, IT 1 J n climates. 

summer or winter, at a given place would apply to all 
places upon that parallel ; without regard to local varia- 
tions of climate. When it is spring at New York it is 
spring at Madrid, Bokhara, and Pekm, but the climates 
of their cities are not alike. 

The exact classification possible to seasons is forbidden 
to climates ; the study of which is complex, embracing 
phenomena varied m character and little allied to each 



56 Chas. W. Holbrook's Lunar Tellurian. 

other. Modern geographers apply the term ''climate" 
to designate the mean temperature of a place. 

The world is indebted to Sir William Herschel and 
Alexander Von Humboldt for the rapid progress made 
in the science of climatology within the past 60 years. 
Humboldt published in 1817 his celebrated treatise on 
the isothermal lines, in which he showed that the de- 
crease of heat with the increase of latitude takes place 
more slowly on the west coasts of the old world than on 
Humboidfs the east of the new. He connected places havms: an 

researches. ^ ^ 

average amount of temperature during the year by iso- 
thermal lines, the convex summits of which fell near 
the west coast of the old world, and their concave near 
the east coast of the new. By combining the decrease 
of temperature by increasing elevation with its decrease 
by increasing latitude, he represented the intersection of 
isothermal surfaces with a vertical plane cutting the 
surface of the earth along a meridian, and showed that 
if the examination of places of equal summer heat and 
equal winter cold were conducted m a similar manner 
by drawing isothermal and isochimal lines, the differ- 
ence between a sea and continental climate would be 
included in the general view. These isothermal lines do 
not follow parallels of latitude. A study of the globe 
will reveal the details as to how the annual rotation and 
oblique motion of the earth in relation to the sun fix the 
Alternatives tropical limits of the sun's apparent decimation south 

of seasons. ^ ^ "■ 

and north of the equator, producing alternate winter 
and summer on either side of the line. The phenome- 
non well understood, it will be evident that the mean 
annual temperature obtained at different latitudes must 
decrease from the equator to the poles. Were the whole 



Chas. W. Holbrookes Lunar Tellurian. 57 



surface of the earth uniform, presenting a monotonous 
surface to the sun, unaffected by disturbed causes of 
mountain ranges, deep valleys, chains of lakes, expan- 
sive deserts, great forests, it would receive a uniform 
and equal degree of radiant heat. In that case the 
mean temperature of every point would be in propor- 
tion to the radius on the parallel of latitude. But the 
mean temperature of places m the same lines of latitude 
differs very materially. It will be observed that the Local 

*^ '' ^ variations. 

lines follow strange and devious courses, though they 

run generally parallel over wide expanses of ocean or isothermais. 

desert country. 

It will be seen by the variations of temperature that 
causes are in operation in different localities affecting 
the mean temperature other than distance from the 
equator. A glance at the isothermais exhibits the fact 
that though remoteness from the equator decreases the 
mean temperature, localities are independent of this 
cause. 

One of the causes of these great variations in the 
same parallel of latitude is the physical formation of 
the earth. The continent of North America m itsPiiysicai 

contour of 

general contour resembles a spherical triang-le of which North 

i-ri-r> 11A America. 

one side stretches along the Pacific, one along the Arc- 
tic, and one along the Atlantic ocean. There are two 
axes of elevation ; one on the Rocky mountains, the 
other on the Appalachian chain. From Labrador to 
California is stretched a great water-shed which, extends 
into four slopes and eight river basins. Three great 
ocean currents sweep along the shores, one southward 
in the Pacific, another eastward in the Arctic, and a 
third nortliw^ard in the Atlantic. The Alleghany and 



68 Chas. W. Holbrook's Lunar Tellurian. 

Eocky mountain ranges divide the face of the country 
into the Atlantic plane and slope, which is washed by 
the Atlantic ocean ; the valley of the Mississippi, lying 
between the Alleghany and Rocky mountains, w^atered 
by the Mississippi and its tributaries, and the Pacific 
slope, extending from the Rocky mountains to the 
shores of the Pacific. This great interior valley begins 
with the tropics and terminates with the polar circle, 
embracing in its area at least three-fourths of the en- 
tire continent. One of the great slopes in this valley 
contains an elevation of 14,000 feet and serves to check 
the winds from the Pacific and bestow on this vast re- 
gion an insular climate. 
Contour of All Northern Europe is a great plane extending far 
into Germany, over a large portion of France, most of 
England, all Ireland, Sweden, and a part of European 
Russia. 

In all this region the peaks of Wales, Scotland, the 
Norwegian chain, and the Ural mountains, constitute 
the only important elevation. Farther south the Pyre- 
nees and the Alps exercise an important agency upon 
the climate, lowering its temperature considerably. Gen- 
eral causes tending to lower the mean annual tempera- 
ture are the following : elevation above the level of the 
sea when not forming part of an extended plane, the 
vicinity of an eastern coast in high and temperate lati- 
tudes, the compact configuration of a continent having no 
littoral curvatures or bays, the extension of land toward 
the poles into the region of perpetual ice. without the 
intervention of a sea remaining open during the winter ; 
mountain chains whose mural form and direction impede 
the action of warm winds. A comparison of the phys- 



Chas. W. Holbrook's Lunar Tellurian. 59 

ical conformation of the coasts of Europe and the east- 
ern part of the United States will show that the chief 
agencies which control climates are directly the reverse Reverse 

agencies. 

in each country. 

Mention has been made of the fact that surplus heat 
at the equator is impelled northward and southward. 

Our planet is surrounded by a shell of atmospheric 
density which acts as a bar to the escape of heat into 
indefinite space. Cold air from the poles constantly 
flows toward the equator to take the place of the as- 
cending currents of hot air. The greater the difference 
in degree of temperatures of Arctics and tropics, the 
stronger these currents are. The Antarctic region has 
for lono; asres been colder than the Arctic. The result ^^^^^ , 

^ ^ currents. 

has been that currents from the south pole have been, 
for so long a time, so strong as to move the surface 
waters of the vast area of southern seas toward the 
equator, producing the trade winds and ocean currents. 

The tropical trade winds give both temperate zones Trade 

T 1 -111 1 1 • T 1 ^vinds. 

west and southwest winds, which are land winds to the 
eastern coasts and sea winds to the western. 

Consequently, the prevailing winds in Europe and 
America are westerly. These land winds in the United 
States tend to give a high summer, and a low winter 
temperature, while the same wind, after crossing the 
Atlantic ocean, bestows upon Europe a much milder 
and more equable temperature. 

To this cause may be attributed the mild climates of 
Ireland, England, Jersey, Normandy, and Germany, 
quite m contrast to the climate of interior Europe. 

Thus, the myrtle blooms simultaneously in Ireland 
and Portugal. In the Orkneys, in the same latitude as 



60 Chas. W. Holbrook's Lunar Tellurian. 



Ocean 
currents. 



Gnlf 
stream. 



Stockholm, the winter temperature is higher than at 
Pans. At the Faroe Islands the inland waters never 
freeze, owing to the moderating influences of the west 
sea winds. 

Ocean currents have an intimate and important con- 
nection with the climate of adjacent coasts. The gulf 
stream contributes essentially to the further modification 
of the climate of Great Britain, giving Ireland her per- 
petual green verdure, and England her perennial hedge. 

A smiilar stream originating far south of Japan greatly 
modifies the climate of the Pacific coast. 

Moisture exercises an important effect upon climate. 

Taken as a whole, all the greater slopes on the Amer- 
ican continent descend easterly toward the Atlantic, 
while the abrupt ones rise on its western aspect. This 
general configuration necessarily gives to Europe a 
moister as well as a more temperate climate than that of 
America in the same parallels of latitude. This would 
be much more obvious but for the Gulf stream and its 
accompanying trade wind. From this source the Atlan- 
tic coast and the Mississippi valley derive a large portion 
of their moisture. The trade wind, fresh from the Gulf 
stream, not only extends its favor along the whole 
Atlantic coast, but reaches over to the Alleghanies, laden 
with vapor. Were the interior valley of the Mississippi 
exposed to the Pacific winds, it would undoubtedly have 
a much milder climate than it now possesses; and were 
the trade winds to cease their supply of vapor it would 
soon change from a fruitful region to a land so barren as 
to unfit it for the abode of man. For as the climate is, 
so is the country which it governs; and as climate and 
soil are, so is man. Upon these primal causes depend 
the character and extent of human civilization. 



Chas. W. Holbrookes Lunar Tellurian. 61 

Use the Tellurian witliout the Day Circle, rectified for 
Dec. 21st, our northern winter. 

The red and blue lines following such strange and illustration. 
devious courses are the Isothermals and Isochermals; 
the red indicating average temperature of regions 
through which it passes during June and July. The 
blue indicate the average temperature for Dec. and Jan. 
The blue lines which traverse the Torrid zone indicate a 
high degree of heat averaging 80 during our winter, 
showing the effect of vertical rays. The blue line 70, 
south of Capricorn, 40 degrees from the equator, shows 
a high degree of temperature, it being their summer. 
But the blue lines 40, 30, nearer the Antarctic Circle, Compari- 
denote much lower temperature during their summer^ 
than the red lines 40-80, at the Arctic Circle during 
our summer, and they are much farther from the south 
pole, clearly proving the greater frigidity of the southern 
pole. North of the equator the blue lines 10, 20. 30, 40, 
run nearly parallel across our southern States, diverging 
only when past mid-ocean and well toward the western 
shores of Europe. Line 40, as an example, gives the 
same winter climate to Weldon, N. C, Bristol, England, 
and Rome. At the same time south of the equator, it 
being summer there, Rio Janeiro, Port Natal, and the 
central belt of Australia have a mean temperature of 80. 
Thus, while blue lines show a hi2:h temperature south Greater ac- 

^ ^ cumulation 

of the equator, they show a low degree north, illus- of cold at 

^ ' -^ . ^ south pole. 

trating at a glance the difference between the effect of 
vertical and oblique rays, as modified by land and sea 
areas. The difference between an Antarctic and an 
Arctic summer is seen by glancing at the blue line near- 
est south pole, marked 30. Notice how far from the 



62 Chas. W. Holbrookes Lunar Tellurian. 

pole it runs, then observe how much nearer the north 
pole the red line 30 runs. The trade winds from the 
south pole are so strong that they impel a mass of water 
northward through the South Atlantic basin, up to the 
equator. A portion is deflected southward again by the 
jutting coast of South America, but the greater mass is 
impelled across the tropics northward, following the 

wind and shores of the Gulf of Mexico; thence along our eastern 
coasts, finally reaching the very confines of the Arctic 
seas. The parallelism of our Gulf stream, as it flows 
northward, and the blue hnes covering it, reveals the 
fact that a volume of heat ascends from a low land lati- 
tude to a high sea latitude. 

Let us suppose a person whose health was such that 
he required a climate of 50 degrees Fahrenheit. He 
would leave Sacramento, crossing the continent to New 
Orleans and Mobile, embarking at Savannah for Gib- 
raltar, taking a detour northward to avoid the heat of 
the Bermudas and Azores. 

At Gibraltar, preferring a sea climate, of 40 degrees, 
our climiate hunter must needs pack and fly by fast dis- 
patch 1,500 miles to the Orkneys, where, let us hope, 
he reaped the benefits of the friendly Gulf Stream. In 
the spring he could go to Norway, thence to Spitzbergen 
for a short summer. 

Observe the red hnes which indicate the average tem- 
perature of the earth during July. 

Summer A high rate in the tropics — it is always hot there. 

cl i m /it PS 

While the mercury would rise to 80 at Cincinnati, 
Tripoli, Rhodes, and Pekm, a singular fact is noticed at 
California; the southwest trade winds give the coast a 
comfortable temperature of 60, but east of the Sierras 



Chas. W. Holbrookes Lunar Tellurian. 63 



it takes a sudden rise of 10 degrees. A short distance 
farther east another rise of JO degrees, inflicting a torrid 
atmosphere upon the vast continent lying between the 
eastern base of the Sierras and the Atlantic coast, from 
Montana diagonally across to Savannah. This elevation 
of the isothermal 80 illustrates in a marked manner the 
fact that land interiors are hotter and colder, alternately 
than sea levels in corresponding latitudes; and that 
western continental coasts have a milder climate than 
eastern coasts. 

Have the climates of zones always been as they now Geologic 
are? No; the climates are constantly and slowly 
changing. 

What causes these changes ? 

The answer is found in the Precession of the Equinoxes, 

It has been laid down that the north pole always 
points to the north star; the earth's axis always inclines 
in one direction; that the poles are always parallel. 
Practically, this is true; life is short, and man is princi- 
pally concerned with to-day and to-morrow\ Geology 
reaches backward and tells us what has occurred. 
Astronomy probes the past and future and prophecies 
for distant coming ages. 

Astronomers teach that the a^xis of our earth projected Poles of the 

. . , . , equinox. 

to the heavens would now reach a pomt withm 1^ 
degrees of the north star; having approached it 12 
degrees since the ancient astrologers drew their magic 
circles. 

Illustrate with the tellurian, rectified for March 20th. 
Rotate the globe, bringing the plane of the eliptic to a 
horizontal position. Let the solar index point at the 
prime meridian when the ecliptic crosses the equator. 



64 Chas. ay. Holbrookes Lunar Tellurian. 

Loosen thumb-screw C ; gently lift the globe by grasp- 
ing the arm B C, withdrawing it from its fixed position. 
Press the arm at B, shghtly moving it eastward, or to 
the right, without rotating the globe on its axis. Observe 
that as you move it by gentle hitches the point of the 
Precession solar index slowly recedes. Each recession of one 

of the ^ '^ 

equinoxes, degree is equal to the change in polar direction in 71 
years; thus, if the vernal equinox occurs March 21st this 
year, in 71 years it will occur March 20th. 

The equinoxes have already receded 30 degrees since 
the earliest data, therefore the signs of the zodiac, w^hich 
are arbitrary, are at this time a month behind their con- 
stellations. Turn the globe slowly as described entirely 
around, returning to correct position; this movement of 
the poles of the axis entirely round the poles of the eclip- 
tic occurs once in about 26,000 years. 

Illustration. Illustrate in another manner; rectify the tellurian for 
Dec. 21st; rotate the arm, describing the annual orbit of 
the earth around the sun, observing that the poles 
always point in the same direction. Lift the whole 
instrument and twist it sidewise, without disturbmg its 
parts. The polar direction has been changed. Continue 
to displace and replace until you have completed an 
entire rotation of the circle of the zodiac. This illus- 
trates the precession of the equinoxes through an entire 
circle once in 26,000 years; the earth meanwhile having 
made diurnal rotations to the sum of 365 tmies 26,000. 

The orbit of the earth in its course through the year 
is not a true circle, but an ellipse; the position of the 

Earth's sun beins; sli2:htly removed from its center. In June the 

orbit ellip , . ^ ^ 

ticai. earth is at its greatest distance from the sun — m 

aiyhelion ; in January it is nearest the sun — in perihelion. 



Chas. W. Holbrookes Lunar Tellurian. 65 



A line piercino; the centers of both sun and earth, ex- Line of 

'^ ^ Apsides. 

tending through aphehon and perihelion, called the Line 
of Apsides, will, if continued indefinitely in both direc- 
tions, pass through the sig^is Capricornus and Cancer, but 
the constellations are not there; 2,000 years ago they 
were, for at that period signs agreed with their constella- 
tions. The slow change in direction of the Line of 
Apsides has caused the astronomical discrepancy. The 
line of apsides is also coincident to the plane of the 
ecliptic. Asa result of precession we know that aphelion Relation to 
is slowly moving eastward, , periheHon westward. Do mates, 
you ask, what have all these indefinite astronomical facts 
to do with climate on our own little planet ? 

Everything. 

Creation is a vast scheme of cause and effect, whose First cause, 
farthest nook and remotest corner is subject to the inex- 
orable mathematics of God the First Logician. 

At the present time, the earth's perihelion occurs in Perihelion. 
January. As a consequence the south temperate zone is 
hotter at that season than is our north temperate durmg 
our summer. The speed of the earth in all its move- 
ments, when in perihelion, is greater in ratio of its 
greater proximity to the sun ; causing a shorter summer 
to the southern hemisphere than is our northern sum- 
mer six months later. In fact, though the summer of 
perihelion is hotter, its brevity prevents the reduction 
of south polar cold in the same degree as at the north 
pole durina; our lon2:er season. Thus the accumulation Greater cold 

^ ^ ^ . at south 

of cold at the Antarctics is not only proportionately pole. 
greater, annually, than at the Arctic, but it also in- 
creases in amount each year. The isothermal lines, as 
seen on the globe^ show the relative accumulation of 
cold at the polar circles. 



66 Chas. W. Holbrook's Lunar Tellurian. 



Second 
cause. 



Aphelion. 



To recapitulate : 

1. The earth has two motions — axial or diurnal, 
orbital or annual. 

There is a time at which the earth in its orbit, having 
passed through perihelion in winter, arrives at a position 
in relation to the illumined hemisphere which causes 
equal day and night : — or equinox. There is another 
time when the earth having passed its summer at aphel- 
ion approaches a like position at the other side of the 
orbit, called equinox — respectively Vernal Equinox and 
Autumnal Equinox. These two positions gradually re- 
cede — that is to say, the day when a line passing from 
the center of the sun to the earth's center would touch 
the equator is always the same day of the calendar and 
is in the same month and sign of the zodiac, for the 
sake of convenience. But, upon this day, that central 
line varies in direction to the distant heavens. Spring 
must come in March, for it is the equinox which gives 
us the date and names, but the constellations seen In 
spring will, at a remote future period, be seen in Sep- 
tember. 
Third cause. 2. The precession of the equinoxes causes a change 
in direction (toward the distant stars), of the line of 
apsides. This will eventually cause — not a change in 
the names of seasons, but a reversal of the climates of 
seasons ; summer will at some distant period be cold, 
much colder than our present winters. 

3. Having learned that the Antarctic region, being 
coldest, exercises a preponderating influence in the causes 
of trade winds and ocean currents ; thus establishing to 
a great extent our present climatic conditions : we know 
that a reversal of polar conditions must cause a reversal 
of effects. 



Fourth 
cause. 



Chas. W. Holbrook's Lunar Tellurian. 67 



Time will come when our northern winter will occur Reversal of 

climates at 

at aphelion. Thus a lone; season of oblique rays and ^^ome re- 

^ ^ 11 mote period. 

greater distance from the sun will cause such accumula- 
tions of frost at the Arctic region as to make it the 
prime factor of our climate. Natural conditions will 
then be reversed — north polar currents will be strong- 
est, the Gulf Stream will be unknown, and trade winds 
will be indicated on marine charts with the barbed 
arrows pointing the other way. 

Such chan o;es are too grad ual to take into human ^'o immedi- 

^ ^ ate danger. 

account. A state of things like that described cannot 
culminate — it is too slow. Even a reversal of present 
climates cannot occur until long after our civilization 
has ripened, decayed, and fallen m the order of nature, 
A northern winter in aphelion occurred before the dawn 
of history. Many thousands of years ago such a period 
covered most of the north temperate zone with oceans 
of ice and snow, but that was prior to the elevation of 
our hig:hest mountains. Those Arctic floods are known Glacial 

^ periods. 

to US as glacial epochs. Their slow descent drove the 
earliest known human beings, the River Drift Men. far First men. 
southward, and they m their turn were exterminated by 
the Cave Men. The northern winter approached peri- 
helion and the Cave Men followed their favorite climate 
northward, where their sole surviving heirs, the Esqui- Their heirs. 
maux, still luxuriate in perpetual snow and a diet of 
grease. Undoubtedly at some not remote period the 
north pole will be reached, as the limit of decreasing 
accumulation at the arctics has not yet been passed. 
The torrid zone slowly extends northward, our temper- 
ate zone as surely approaching the Arctic circle. This 
process is so slow that perhaps the best illustration of its 



68 Chas. W. Holbrook's Lunar Tellurian. 



effects may be found in the history of modern civiliza- 
ciimate and tion. Intellectual ener2:y exists only under proper cli- 

intellect. . ,. . ^ -, • , 

matic conditions. Constant high temperature prevents 
a marked rise above barbarism. A high rate of human 
achievement is only compatible with temperate zones. 
Eecall to mind the gradual northward advance, during 
Vast transi-the last 3,000 years as recited in history. From Thebes 
to Athens, from Athens to Rome, from Rome to Paris, 
London, Berlin, New York. 

Civilizations rise and fall ; races of men appear only 
to disappear ; each epoch of human transition being 
allied to, if not coincidental with^ a change in terrestrial 
climate. 

Longitude and Time. 

Longitude is the angular distance between two meridi- 
ans, measured upon the equator or any parallel, usually 
East and reckoned east and west from the prime meridian. Dis- 

west longi- . ^^ ^ . T 

tude. tance to the right is called east longitude ; to the left, 

west longitude. Every point on a given meridian has 
the same longitude. Any two meridians include an arc 
having the same number of degrees whether measured 
upon the equator or a parallel. But the absolute length 

Solar of the arc of a parallel is in proportion to the radius of 

its circle. Thus, m regard to the sun's dechnation at 
equinox, an observer at the equator would see a circle 
described from east to west through zenith ; while the 
circle as seen at the arctic zone would be very small 
and far south of east, west, and zenith ; though the 
time of the sun's course from rising to setting would 
be 12 hours at either place. 

Distance, as expressed by the term ''longitude," is 
measured on the earth in degrees, minutes, and seconds. 



Chas. W. Holbrook's Lunar Tellurian. 69 

Distance, as expressed by the term ''time," is reckoned 
by months, days, hours, and seconds. 

A year is the limit of time as appUed to longitudinal 
distance, because the geographical division of longitude 
corresponds to the mathematical division of a year. 
The earth, as you observe on the crlobe, is divided into Degrees and 

/ . • -, • • hours. 

360 degrees, the space between two meridians compris- 
ing 15 degrees which is equal to one hour of mean solar 
time, each degree being equal to four minutes. 

Bring the Calendar index to March 20th, and the 
meridian of Greenw^ich to the solar index at J. Ob- 
serve that longitude is reckoned east and west from 
this meridian. It is noon at Greenwich, and, as the 
earth rotates to the east, all longitudes east must have 
passed the solar index, therefore it is later in the day 
at all places whose longitude is east of the prime me- 
ridian. 

It is afternoon at Constantinople, evening at Calcutta, variation ot 
midnight and the beginning of another day at longitude a day. 
180. Rotate the earth and bring 180 to the solar index. 
It is midnight at Greenwich, noon at 180, morning at 
Calcutta, and evening at Constantinople. Can noon and 
midnight occur every 12 hours? Yes, midnight occurs 
every instant, and noon is perpetual. Mark the night 
shade opposite on the meridian of Greenwich at mid- 
night. 

Rotate the globe and observe that the point of noon 
under the solar index and midnight on the night shade 
are fixed while the entire map of the globe passes these 
points. 

Time is fixed in space and variable upon the earth, 
for it IS always noon under the vertical ray and mid- 



70 Chas. W. Holbrook's Lunar Tellurian. 

night 180 degrees distant in either direction. Bring the 
prime meridian to the solar index. 
Hypothetic- If the earth remained viotionless and a carrier pigeon 
of pigeons, were given wing at Greenwich for Chicago, he would 
have to fly westward 15 degrees an hour for 6 hours to 
reach Chicago at 6 o'clock, and a further journey of 6 
hours at the same speed to reach meridian 180 at mid- 
night. Continuing his flight would he not see the sun 
rise in the west at 6 o'clock in the morning at Calcutta, 
having seen it sink in the east the previous night at 
Chicago ? 

The bird flew in one direction the entire journey in 
24 hours and saw the sun in opposite directions at night- 
fall and morning. 

The carrier pigeon exactly describes the apparent mo- 
tion of the sun. 

He can make a much easier tour of the circle in 24 
hours in fact, for he has only to perch at Greenwich and 
the earth's axial movement will carry him around with- 
out effort ; m this case the sun will rise in the east and 
set in the west. 

Let us suppose a pigeon on wing at 0, noon, March 
20th. 

The earth would make an entire revolution under him 
in 24 hours and he would perch hot, tired, and exhaust- 
ed after a noon of 24 hours duration. Imagine him 
taking flight the next day at noon from Greenwich for 
Chicago : Arriving there after a three hours' journey of 
15 degrees an hour. What time would it be m Chicago ? 

Nine o'clock in the forenoon ! 

He arrived before he started ! 

When it is noon at Greenwich it is 6 a. m. at Chicago. 



Chas. W. Holbrookes Lunar Tellurian. 71 

The pigeon flies westward away from the sun one-half 
the journey ; rotation of the earth moves Chicago toward 
the sun the other half, or three hours. 

Restiijg at Chicago three hours, the bird sees noon for 
the second time after a duration of only 6 hours. 

Starting again he flies eastward for home, arriving at 
noon the next day ; how far did he travel ? 

It IS but 90 degrees from Chicago to Greenwich, yet 
the pigeon flew 360 degrees ; for did he not fly the en- 
tire circuit of space from the solar index back to the 
same ? At what rate did he travel ? He could have 
made the journey easier by flying to the north pole in 3 
hours, and perching when it was 3 p. m. at Chicago, and 
9 p. M. at Greenwich. Waiting until it was 9^ a. m. of 
the followmg day, at Greenwich, he would fly southward 
2^ hours and perch at home after a 5^ hours' flight 
under perpetual noon and a rest of 18^ hours. Or he 
might have flowm from Chicago to the south pole, arriv- 
ing there when it was 9 p. m. at Chicago, and 3 a. m. at 
Greenwich. But his journey must have been continu- 
ous for he would have to start on his return instantly 
and gain a half hour to perch at Greenwich at noon. 

Let two pigeons start from the equator at 0, noon, 
March 20th, one going eastward the other w^estward at 
the rate of 15 degrees an hour, taking wing from a ship 
in the Gulf of Guinea. They would meet at midnight 
— where ? 

They would alight on their perch, w^hence they had 
flown. Resting six hours, they start again, one flying 
from sunrise, eastward, toward noon ; the other flying 
westward toward midnight. In 12 hours w^ould they 
not meet on perch at sunset March 21st. Trace their 



72 Chas. W. Holbrook's Lunar Tellurian. 

journey with the globe, then map out the same journeys 
by men travelmg on the earth at the same rate of speed, 
and observe the difference between the variation of time 
by traveUng eastward or westward. 

To find the Longitude of any Place. 

Bring the meridian of the place to the solar index ; — 
the degree east or west of is found where the merid- 
ian crosses the equator. 

To find the Latitude of any Place. 

Bring the given place to the- solar index adjusted so as 
to cover it ; rotate the globe and find the degree indi- 
cated on meridian 170. 

Sidereal and Solar Time- 

A sidereal day is the interval between the moment a 
fixed star is on a meridian, and the moment when it is 
next on the same meridian. A solar day is the time 
from noon of one day to noon of the next day, or when 
the sun is on the same meridian. Illustrate with the 
tellurian rectified for March 20th — solar index at Prime 
Meridian and in line with a distant window which stands 
for a star. 
Illustration. Eotate the globe once, exactly, on its axis without mov- 
ing the arm. This illustrates a solar day, and if the 
earth had only an axial and no orbital motion you will 
perceive that the solar and sidereal days would be alike, 
because your solar index would remain in line with your 
w^indow. Now move the arm slightly and you will 
observe that the solar index does not point at the same 
meridian. Call it one day's interval, and explain that as 



CiiAS. W. Holbrookes Lunar Tellurian. 73 

the earth has made one exact rotation on its axis, the 
star only is on the meridian ; showing a sidereal day. 
Must not the globe be moved still more to bring the 
meridian under the solar index ? 

Durino' one diurnal motion of the earth on its axis, Variation 

^ ' caused by 

the orbital motion carries it eastward nearly 1° ; there- ^i-bitai 

fore, it must perform 1° more than one exact rotation to 

bring the same meridian to noon of the second day — or 

between two successive upper transits of the sun. Or, 

to repeat in other words, if the sun and star cross the Conjunc- 

^ tion. 

meridian together at noon to day, to-morrow the star will 
cross about four minutes before the sun. This variation 
extended through a whole year, makes it necessary for 
the earth to perform one entire revolution more on its 
axis to make solar days than would be required for the 
same number of sidereal days. This fact is made appar- 
ent by your use of the tellurian, for you observe that by 
each slight movement of the arm, you separate your star 
meridian from your sun's meridian ; and if you allow 
the globe to rest, it is necessary to make an entire circle 
of the arm before you can brins: your star and sun a2:ain Second con- 

•^ ^ *^ ^ juDCtion. 

in conjunction. 

The solar day does not always differ from the sidereal 
by precisely the same amount because of the unequal 
rate at which the earth moves at different times of the 
year, in its orbit at the plane of the echptic. Time 
measured by a meridian sun is called apparent time. The Apparent 
average length of solar days for the year is mean time — ^^^^^^ ^j^^^ 
the mean solar day; thus constituting the civil day of civu day. 
24 hours, beginning at midnight with the sun at lower 
transit. It is divided into two periods, each of twelve 
hours ; from the lower to the upper transit — midnight 



74 Chas. W. Holbrook's Lunar Tellurian. 

to noon — and from the upper to the lower — noon to 
midnight. 

The interval by which apparent time differs from mean 

Equation of time is Called the equation of time. The sun's change of 
right ascension is sometimes faster than if it moved on 
the equator, and sometimes slower ; therefore, the equa- 
tion must sometimes be added to, and sometimes sub- 
tracted from, apparent time. Its greatest additive value 
is 14:J minutes about February 11th and its greatest sub- 
tractive value 16^ minutes about November 3d. The 
equation of time is zero ; mean time and true time are 
the same four times in the year ; Apr. 15th, June 15th, 
Sept. 1st, and Dec. 24th. 

Local time. Local time is the time of day (solar or sidereal) on any 
given meridian at any instant. The beginning of a day 
is determined by the transit, across a given meridian, of 
the sun or star which has an apparent diurnal motion of 
15° per hour ; therefore, the local time at two different 
meridians at the same instant must differ at the rate of 
4 minutes for each degree, or 15° every hour. Since 
the diurnal motion of the earth is from west to east, it 
follows that time is later at places east of a given merid- 
ian and earlier west of the same meridian. 

The Moon. 

Our satellite resembles the earth in form ; in size it is 
one-quarter as large ; in volume, one-fiftieth. Seventy 
million moons could be stowed within the enormous bulk 
of the sun ; yet the apparent size of sun and moon is 
nearly the same. This is owing, of course to their rela- 
tive distances, the moon being less than 240,000 miles 
away, while the sun's rays reach us across the abysmal 



Chas. W. IIolbrook's Lunar Tellurian. 75 



depths of ninety million miles. You may reduce the 
apparent sizes of large and small objects by varying their 
distance from the eye. The dark spots on the moon are 
the yawning craters of extinct volcanoes ; the larger 
darkened areas are shadows of high mountains. The 
moon has been condemned as a defunct orb, without 
moisture, atmosphere, or life ; but late research claims 
to have discovered signs of vegetable life. 

It is not known whether this condition is due to 
infancy or old age. 

Civilization, with its telescope, calculus, and spectrum 
has not existed long enough to observe a great geologic 
change. 

The sidereal revolution of the moon around the earth Lunar days. 
is once in 27-J days, but as the earth's orbital movement 
carries it constantly forward, the " face " of the moon is 
at the same point in relation to the sun once in 29^ days. 
This phenomenon is similar to the distinction between 
the sidereal and solar day as illustrated with the 
tellurian. 

The moon always turns the same side toward the 
earth, therefore it turns on its axis once a month. One- 
half its surface is illumined 15 days by the sun and 
becomes, by accumulation of heat, much hotter than our 
torrid zone. 

At the same time the dark half has ample time to radi- 
ate its heat and accumulate a correspondingly intense 
degree of frigidity. 



76 Chas. W. Holbrook's Lunar Tellurian. 



CHAS. W. HOLBROOK'S LUNARIAN. 




Cut No. 2. 

Description. Tlie Lunarian is adjusted for use as shown in the cut. 
Mount the globe at the center of the base. Screw on 
the moon precisely as follows: Loosen thumb-screw X, 
tigliten thumb-screw N, remove the pointer, or lunar 
index 0; press the collar down over the post at X, take 
hold of the cross-piece at N and turn to the right, press- 
ing downward. When you have screwed on the moon 
tighten thumb-screw at X. Rectify for Dec. 20th by 
bringing the calendar index Y to the winter solstice. 
Place the sun Z opposite Y, let the solar mdex P point 
at meridian 95. 

If you will now mark one side of the moon, and turn 
that side toward the sun, calling it the ^^face" of the 
moon, screw up tightly at N, adjust the dark shade 
away from the sun and screw up at U, the apparatus is 



Chas. W. Holbrook's Lunar Tellurian. 77 

ready for use. To show the moon receiving the light 
of the sun above or below the earth, hold it at a dis- 
tance from the earth, in an opposite direction to the 
pupils. Rotate the arm toward the west and observe: — 

1. The ''face" of the moon, whether visible or invis- illustration, 
ible always points toward the earth. 

2. The "face," to be visible, must be directed toward 
the sun. Some portion of the ''face " half of the moon 
is always visible from some place on the earth except at 
eclipse. The sun forever shines upon and irradiates a 
half of the moon except when the moon is eclipsed at 
*'fall," on the dark side of the earth. 

3. The face of the moon disappears by rotating into A^erfect 
darkness J and though constantly facing the earth is, for moon. 

a portion of time during each lunar day, invisible by its 
own shadow. The black shield on this mechanical moon 
well illustrates the obtrusion of a lunar night by the 
intrusion of the moon's surface into darkness. 

4. The amount of luminosity visible to an observer 
depends upon whether the moon's course is during day 
or night. If during the day the sun's light extinguishes 
the lunar orb — if during night the sun's light is re- 
flected from the lunar orb. The observer will, in the 
latter case, see the moon; the visible area being in ratio 
to the parallelism of his line of vision to the solar rays 
which illumine the moon in opposition. 

Astronomers tell us that the moon's orbit is inclined 
to the plane of the ecliptic 5 degrees; which means that 
while the earth goes swimming along the plane, the moon, 
like a flying fish alternately leaps above and dives below 
the level. Would not the effects be the same if the 
moon rode horizontally and the plane vibrated with a 



78 Chas. W. Holbrook's Lunar Tellurian. 



wavy motion once a month ? So far as our mechanical 

illustrations of the moon's movements are concerned, the 

051^1%^*^ of ^^^^^ ^s ^^^ same. Remove the earth and mcline the 

the ediKic^ P^^^^ of the ecliptic by inserting projection 2 (cut No, 3) 

at the aperture 2 (cut No. 2.) 




Cut No. 3. 



Rotate the arm, and observe that, if you have the 
earth inclined with the north pole turned farthest from 
the sun, the moon is in perigee, nearest the earth, dur- 
ing the night; in apogee during the day, in the winter 
season. Insert the lunar index 0, and it will trace 
upon the earth a line running 5 degrees north of the 
plane of the ecliptic and the same distance south, 
illustrating, exactly^ the fact that the maximum variation 
of moon's point of sunrise and sunset during the year is 
57 degrees, its minimum variation being 37 degrees. 
This fact is apparent when we reflect that owing to the 
inclination of the earth's axis, 23|- degrees, the variation 
of sun's place on the horizon is 47 degrees; and the obli- 
quity of lunar orbit 5 degrees above and below may add 
or subtract 10 degrees to and from 47 degrees. 



Chas. W. IIolbrook's Lunar Tellurian. 79 



The Phases of the Moon. 

Have the globe properly adjusted, meridian 95 directly 
above Dec. 21st. 

Place the sun Z at March 20th, and adjust the solar 
index P to indicate the Prime Meridian at the equator. 
Adjust the moon shade and bring the Calendar index to 
November which is your point of observation. Look 
across the curve of the globe and by rotating the arm 
you can describe all the phases of the moon. 

High and Low Moon. 

Rectify for December by placing; the sun in its first Variation of 

^ J r o height for 

position. Rotate the Hobe and brina; the United States winter and 

1 summer. 

to the dark side of the earth. 

Rotate the arm, calendar index at December. Adjust 
the moon shade to show ''full" moon at night. Rotate 
the arm and observe that the lunar-index indicates lati- 
tude 28 north, during the night when the moon is visi- 
ble, descending to 28 south during the day, when the 
dark side is toward the earth. This is a '^ high " or 
winter moon. To show the ''low" summer moon, 
rotate the earth on its pivot at 2, reversing its position; 
or let the earth remain, and place the sun at June, the 
moon at December with the dark shade reversed. In 
this position the moon is only visible when low. Varia- 
tion of plane of lunar orbit is very slight. The differ- 
ence between high and low moon is caused by the 
change from winter to summer, of the position of the 
northern hemisphere in relation to day and night. 



80 Chas. W. ITolbrook's Lunar Tellurian. 



Perigee and Apogee. 

The lunar orbit is elliptical in form. Lunar apsides, 
an imaginary line extending from the moon's place when 
at greatest distance from earth to the nearest limit in 
perigee, has a very eccentric motion. This line is never 
straight and seldom touches the earth. It makes a com- 
plete revolution once in nine years. Apogee and Peri- 
gee are in opposite signs of the zodiac but do not bisect 
the circle. The moon's apogee in the constellation Aqua- 
rius in January, 1878, made the circuit of the zodiac by 
January, 1887, its motion being quite uniformly vibra- 
tory; but perigee darted forward and backward with 
strides which covered one sixth of the circle or m.ore. 

The effect of perigee is seen in a total eclipse of the 
sun — apogee causing an annular eclipse. The lunar 
apse revolves in one-half the time required for the saros. 

Harvest Moon- 
As the moon performs her journey around the earth 
in a month, the daily advance eastward is 12 degrees. 
If the lunar orbit were in the plane of the ecliptic it is 
plain that we should have two eclipses during the 
month, but we see our mechanical moon tracing an orbit 
which is part of the time above, the other part below 
the ecliptic. 
Difference If you will rotate the arm and move the moon slowly, 
between the you will observe that at Capricornus and Cancer the lunar 
hinar mbit^ orbit is nearly parallel to the plane, and equator. When 
Equator at following this coursc the moon's rising for a few days is 

Aries and , i . i ^ 

Libra. at nearly the same hour. 

But when the moon approaches Aries and Libra its 



Chas. W. Holbrook's Lunar Tellurian. 81 

path is much inclined to the equator; at Aries ascending 
to the equator, at Libra, descending toward the equator. 
When the moon ascends, three or four successive risings 
will occur at nearly the same hour, because the horizon 
of an observer in latitude 45 will be carried toward it at 
a slight angle. 

When descending in Libra, the moon will rise at 
nearly the same place but at long intervals, for a few 
nights, because the horizon approaches moonrise more 
obliquely. 

To illustrate: Bring the moon to Aries and rotate the 
earth on its axes, observing that your horizon approaches 
the moon's path as it ascends to the equator. Whereas, 
when the moon is full at Libra, at vernal equinox, your 
horizon and the moon's path diverge. In the former 
case moonrise occurs at nearly the same hour at places 
widely separated ; in the latter case, moonrise occurs at 
nearly the same point on the horizon but at hours widely 
separated. 

When the moon is full in Aries the sun is in Libra, 
the autumnal equinox is at the eastern horizon. This 
is the harvest season in England where the name was 
given to the harvest moon. 

Nodes- 
Adjust the lunarian as described; the globe, as ex- 
plained by Cut No. 3. Plane of the ecliptic is inclined in 
such a manner as to dip its northern and elevate its 
southern parahel. Rectify the lunar index to cross the 
ecliptic at the prime meridian, as you rotate the arm. 
The moon's orbit crosses the ecliptic. It will cross again 
at meridian 180. 
6 



82 Chas. W. Holbrook's Lunar Tellurian. 



These points are nodes. 
Where Each sidereal revolution of the moon comprises two 

nodes , , ^ . ^ 

occur. nodes. The ascending node is a point on the ecliptic 

where the moon crosses in passing from below. The 
descending node is the point crossing in descending. Bear 
in mind that nodes do not relate to the equator, but to the 
plane of the ecliptic. As the lunarian is arranged, the 
ascending node occurs March 20th, the descending, 
Sept. 23d. 

If sidereal and synodic revolutions were identical, 
nodes would always occur at the same points. But the 
moon makes two nodes in 27^ days, the orbital progres- 
sion of the earth impels the satellite forward, changing 
pos'tion so much that the moon must advance 2\ days 
farther in orbit to recover the same relation to the sun, 
or the same jjJiase. 

From ascending node to ascending node is a nodical 
revolution of the moon. 

From full moon to full moon is a synodical revolution 
of the moon. 

Nodes relate to the moon's place as seen from a star, 
and they occur only at the plane of the ecliptic. 

Phases relate to the appearance of the moon as seen 
from the earth. Phases occur every 29|- days, while 
nodes, occurring oftener, must vary in position. They 
do, in fact, recede about 19 degrees during one year. 
A given node passes around the entire circuit of the 
ecliptic in 1 8 years. The place of nodes are sometimes 
between the places of perigee and apogee; at other times 
are identical to them. 

Illustrate with the Tellurian : Rectify for December 
as shown in cut No. 1. 



Chas. AV. Holbrook's Lunar Tellurian. 83 

Incline the upper half of the day circle by bending 
it away from K toward and beyond L, letting it rest 5 
degrees above the plane of the ecliptic, after bringing 
the latter to a horizontal level. The hoop represents 
the half orbit of the moon above the ecliptic. If the 
hoop were extended on the same plane entirely around 
the globe, it would represent the entire orbit of the 
moon. The pivots or nodes of the hoop describe the 
two points when the orbit crosses the ecliptic. Rotate 
the arm slowly, observing that 

1. If the moon's orbit cross the ecliptic twice in 27^ 
days, it would make during the year thirteen each as- 
cending and descending nodes, and a fraction over. 
This fraction gives the moon in the year 1888 fourteen 
ascending and thirteen descending nodes. 

2. As the phases of the moon are governed by its po- 
sition to the sun, it follows that the nodes and phases 
are irrelevant to each other. 

3. That a node is not necessarily made at the equi- 
noxes, or at any other given point. 

4. That a ''high" moon may be 5 degrees below the 
ecliptic, a ''low" moon 5 degrees above the ecliptic; 
the terms "high" and "low" relating to the equator 
only. 

5. That a high moon may traverse a low node, that 
is, a high moon is not necessarily at the highest point 
from the ecliptic, and vice versa, 

6. That the moon passes through the signs of the 
zodiac once each sidereal revolution. 

7. By the Lunarian. Cut No. 2. 

That the sun is in the same sign as the moon when 
the moon is new ; that the earth as seen from sun or 



84 Chas. W. Holbrook's Lunar Tellurian. 

moon would always appear in the opposite sign ; that 
the earth and sun are in the same sign when the full 
moon is eclipsed, but not when the moon is full. The 
full moon is never exactly in line with the earth and 
sun. When the sun sets in the west the moon may be 
in the opposite sign, but not at an opposite point — if 
the sun set Sept. 23d at the first point of Libra, the full 
moon will rise in the last of Aquarius. 

The straight line from setting sun to rising full moon 
does not pass through the center of the earth nor across 
its edge at the feet of the obseiver, but at a distance 
from the earth. 

Eclipses. 

1. When the moon is between the earth and sun it is 
^^new" and invisible, 
anmiiar^^ Illustrate by placing the moon in this position, the 
eclipses. shade hiding the moon from the earth. If the new 
moon approach a node the sun will be eclipsed. If the 
moon is farthest from the earth, in apogee, the eclipse 
is annular. If the moon is nearest the earth, in perigee, 
the eclipse is total. A dime held before your eye w^ill 
eclipse wholly or partially a large, distant object if you 
vary its distance. 

A dime placed upon a nickel will illustrate an annu- 
lar eclipse of the nickel. A dime placed upon another 
dime will totally echpse it. The moon is so far away 
in apogee, that it will not entirely obscure the sun's 
disk, and the latter will display around the moon an 
annular ring of light. 

The shadow of the moon is conical in form, the apex 
of which will barely reach the earth, while, with the 



Chas. W. Holbrook's Lunar Tellurian. 85 



moon in perigee, this shadow will more than reach the 
earth, forming a dark spot about 180 miles in diameter. 
The sun is so large that if the moon approach within 
15 degrees of a node there will be a total eclipse, visible 
to some portion of the earth ; if it approach within 30 
degrees the eclipse will be partial. The total shadow 
called '' umbra," of the moon, is small at the earth's 
surface, compared to the partial or *^ penumbra " shad- 
ow, which is about 4,000 miles, so that an observer 2,000 
miles from the scene of a total or annular eclipse may 
witness a partial eclipse. It is possible for an eclipse Both at the 

^ r i- -L game time 

to be both annular and total to different observers, for possible, 
example, the eclipse of March 5, 1886, visible as an- 
nular at Tampico at sunset and New Guinea at morn- 
ing, might be total to an observer at Kingsmills, me- 
ridian 180 — at noon, because the latter place is 4,000 
miles nearer the moon than the former, and the moon 
would appear ^^ larger. This phenomenon could only 
happen when the relative distances of moon and sun 
at syzygies were such that the moon's shadow would be 
too long to reach the nearest part of the earth, and not 
long enough to reach the earth's center. The moon's 
shadow travels across the earth at an absolute velocity Velocity of 

. moon's 

ot 2,000 miles an hour ; sufficient to carry it across the shadow, 
earth's disk in four hours. The rotation of the earth 
reduces this one-half at the equator where the shadow 
falls vertically. Over the curvature of the earth at 
morning and evening the shadow passes more quickly; 
also at increased latitudes, on account of slower motion. 
To our human vision the sun and moon differ so little 
in size, and the velocity of the shadow is so great that 
the duration of total and annular eclipses is short, last- 
ing but a few minutes at one point of observation. 



86 Chas. W. Holbrook's Lunar Tellurian. 
I 

A solar eclipse begins on the western edge of the 

disk, the moon approaching the sun always from the 

west, in the same manner as a meridian of the earth 

approaches, overtaking the sun, and passing across its 

Umbra and (jig]^ to the east. A spectator at the moon, durina: a 

Penumbra. ^ ^ 70 

solar eclipse, would observe a small black spot moving 
eastward upon the earth, this spot surrounded by a 
much larger round shadow. 

The spot is the umbra, the shadow the penumbra ; the 
umbra is the total obscuration, the penumbra the partial 
obscuration. The sun is not affected when eclipsed — 
we are simply unable to see it. 

Umhra and penumlra of the moon during a solar 
eclipse may be illustrated with the Lunarian as follows : 

Place the sun a few feet from the earth, the moon 
between them. With the flat of a knife-blade or paper- 
cutter, press a cord against the earth opposite the lunar 
index. Draw the ends of the cord backward away from 
the earth across the upper and lower edges of the moon, 
fastening them to the sun beyond. The cone between 
the moon and earth is the umhra, and the flat blade will 
describe the area of totality upon the earth. 

Now draw the sun backward a little and hold the 
cord against the globe with the edge of the blade, bring, 
ing the cone to a point, describing the umbra of an 
annular eclipse. The penumbra will be shown by pass- 
ing the cord from the center of the sun across the moon 
to the earth. 

A good illustration of solar eclipse may be made with 
the Tellurian, 
niustration Place the globe on the arm, as in Cut 1, put on the 
day circle and night shade. Take a position, on the 



Chas. W. Holbrook's Lunar TellurIxVN. 87 

dark side of the globe, at such distance that, with the 
moon in your hand, you may obscure the whole globe 
— a total eclipse. Extend the moon farther from the 
eye and the day circle will represent the annular ring of 
light which is seen during an annular eclipse. In this 
case the globe is the sun and yourself the earth, the 
umbra reaching your eye. 

The area upon the earth covered by the penumbral 
shadow of the moon during an eclipse of the sun is 
called the solar ecliptic limit. It is so lars-e that, if aSoiar 

^ '^ ecliptic 

lunar eclipse occurs very near a node, there must be one limit, 
and may be two solar echpses at preceding and follow- 
ing conjunctions. Thus, there may be as many as six 
eclipses while the sun passes the two nodes. 

As a result of the backward motion of the nodes 
another may occur during the year, the greatest num- 
ber of possible eclipses in a year being seven, of which 
five are solar and two lunar. 

If an eclipse of the sun occur in passing: each node, Lunar eciip- 

^ ^ ^ tic limit. 

the lunar ecliptic limit is so small that the moon may 
escape an eclipse when in opposition, the previous and 
subsequent orbital courses carrying it above and below 
the shadow of the earth. 

Eclipses of the Moon. 

In previous experiments with the Tellurian, concern- 
ing the phenomena of light and darkness, it was seen 
that the sun eternally illumines space in all directions. 
Any planet, satellite, orb of any degree, flying asteroid, 
or floating speck will, if opaque, have its one portion 
illumined, , while its other part will be dark. Any orb 
receiving light from the sun will cast a shadow away 



88 Chas. W. Holbrook's Lunar Tellurian. 

from the sun. The earth moving along the places of 
the ecliptic casts a shadow which, like a comet's tail, 
always points away from the sun. This shadow moves 
at the same rate of speed as the earth, measured by 
degrees, its velocity being greatest at its farthest ex- 
treme does not affect the fact of degrees as distinguished 
from miles. 

This shadow of the earth may be shown with the lu- 

iiiustration. narian, adjusted as in cut 2. Draw a cord around the 
globe, crossing the north and south pole, extending it 
beyond the moon four times the distance of the moon 
from the earth, bringing the ends together. This cone 
is the umbra, and the moon is eclipsed in the center of 
its diameter. Move the sun away four feet, and fasten 
a cord at the solar index, drawing the cord across the 
upper and lower edges of the earth and beyond. This 
illustrates the penumbra. Within the penumbra there 
is light from a portion of the sun only ; within the 
umbra no solar light reaches. 

Sizes of The diameter of penumbra where the moon enters is 

Umbra and 

Penumbra about five times the moon's diameter. The diameter of 

at the moon. _ _ , . ^ ^ ^ . ^ 

umbra where the moon enters is about two and two-third 
times the moon's size. The edge of the umbral shadow 
is so indistinct — gradually fading into penumbra — that 
the moon, to be totally eclipsed, must pass its own diam- 
eter into the total shadow once and a half. 

The area of totality for lunar eclipses is, therefore, 
very small. If the moon's orbit were identical to the 
plane of the ecliptic, the moon must pass through the 
umbra every month. There would then be a total 
eclipse of the moon when in opposition, and of the sun, 
when in conjunction. We have illustrated the orbit of 



Chas. W. Holbrook's Lunar Tellurian. 89 

the moon as inclined to the plane, and, at the moon's 
real distance (120 times the moon's diameter from the 
earth), it will readily be seen that opposition and con- 
junction are generally passed above or below the earth's 
shadow. 

The earth and shadow move in the plane about one ^^^^ocity of 

^ earth 8 

degree daily, but the moon advances about thirteen ^^ladow. 
degrees daily. If the earth had only an orbital motion 
the moon would appear to pass quickly through the 
shadow. Owing to the axial rotation of the earth the 
progress of the moon through the shadow may be much 
retarded by the fact that an observer at the earth would, 
by his rapid eastward movement, keep the moon and 
shadow in occnltation, thus prolonging an eclipse, from 
first to last contact, to several hours. 

An eclipse of the moon begins on its eastern edge 
and ends on the western. When the moon overtakes 
the sun the sun is eclipsed, beginning on the western 
side; when the moon overtakes a shadow the moon is 
eclipsed from the eastern. 

During a lunar eclipse the moon is entirely enshrouded, 
the sidie nearest the sun being eclipsed, and the farther 
side black with intense darkness. At such a time, a 
man on the moon would say that the big earth passed 
betAveen him and the sun from east to west, and to him 
the earth would be an immense black spot. The whole 
firmament would glow with a subdued light. 

Lunar Journey. 

A pleasing and entertaining use may be made of the 
lunarian by following the phases of the moon as described 
in an almanac. (The writer, without wishing to be invid- 



90 Chas. W. Holbrook's Lunar Tellurian. 

ions, begs to say, parenthetically, that he found Ayers' 
Almanac to be the most exact and minute in its lunar 
records. It is quite on a par with the Nautical Almanac 
published by the U. S. Government, so far as it goes, 
and can be had gratis of any druggist or storekeeper.) 

In following a lunar course, always place the sun oppo- 
site the date, for it is the sun's position in the heavens 
which gives us the constellation, month and date. You 
observe in the spaces divided into constellations three 
characters ; a small astronomical sign at the left corner, 
the name of the constellation and a figure illustrating the 
constellation. We will ignore the signs, advancing by 
names and subjects. 

The name is position for frrst of space and the subject 
for last of space. 

Adjust the lunarian as shown in cut No. 2. 

First night Suppose we begin with July 9, 1888. Place the sun 
in position opposite that day, the solar index adjusted to 
the plane of the ecliptic when horizontally level. New 
moon on last of Gemini. Rotate the arm to position 
directly above the twins, as they are described airing 
themselves in the balmy atmosphere of summer. San 

Eclipse of and moon are in conjunction, rising and setting at nearly 

iiiusu-ated. the samc hour. The moon is, of course, invisible at the 
earth, as it approaches the solar ecliptic limit at ascend- 
ing node. The approach to the node is from below the 
plane of the ecliptic, and, as tho moon enters the limit of 
totality, its upper limb obscures the lower limb of the 
sun for a brief space of time, sending the shadow darting 

Where across the lower limb of the earth. In this case, the 

visible. 

eclipse is visible only in the southern Indian Ocean, and 
is so brief that before the diurnal rotation of the earth 



Chas. W. Holbrook's Lunar Tellurian. 91 

can bring a southern continent into point of contact, 
the Gchpse is over. This eclipse occurs when it is our 
night and when we are brought into dayhght, the moon 
is extinguished by the greater force of the sun's Hght. 
We never see the moon except when it is in position to 
reflect to us the sun's light. If the moon be between us invisible 

moon. 

and the sun we might be able to see the dark side, as we 
see the black disk of our imitation moon, but for the fact 
that the atmosphere in its prime capacity so thoroughly 
mixes and equalizes the rays of light as to prevent the 
sight of a new moon. So that, at an eclipse of the sun, 
the moon, as yet invisible, intrudes her black disk across 
the sun ; without sound or warning — appearing sud- 
denly from nowhere and disappearing into the same neb- 
ulous limbo. 

A new moon is invisible to all parts of the earth 
except at times of solar eclipse ; at such times it is visi- visible new 

^ ■'• ^ moon. 

ble only at such places as are covered by the lunar 
shadow. A full moon is visible to all parts of the earth, 
except when eclipsed, at which time it is visible but 
not bright — the degree of intensity of its obscuration 
depending upon whether the shadow be umbral or 
penumbral. 

July 10th, second night. 

Moon sets 70 minutes later than the sun, having; Second 

' ^ night. 

advanced 12 degrees in its orbit (that difference in time 
constituting the difference between the moon's solar and 
sidereal days) in the first of Cancer. Place the arm over 
the name. On this nio:ht the slender crescent moon is Crescent 

. . moon. 

visible a short time after sunset. Take a position where 
you can look across the edge of the globe at the sun and 
you will discern the slender crescent-shaped rim of the 



92 Chas. W. Holbrook's Lunar Tellurian. 

moon, if yon have properly adjusted the moon shade. 
You will notice that the moon appears to be nearer con- 
junction than on the previous night, when invisible. And 

Nodes. so it will appear for another night, but you will bear in 
mind that the moon has crossed the plane, is now above it, 
and that the plane of the moon's orbit is not comcidental 
to the plane of the ecliptic (the earth's orbit) but inclined 
to it : also that this 2 inch moon at a distance of 20 feet 
and the sun a mile and a half away, would cast a shadow 

Moon's above the earth. AY hen the moon is near a node, the 

shadow. 

plane of its orbit is inclined to the plane of the ecliptic, 
and at the rate of speed with which the shadow advances, 
you can readily see how at noon of one day that shadow 
might touch the southern extreme of the earth, losing 
itself in space in an hour, because the eastward advance 
of the moon is so much more swift than the upward. 
When the moon's course lies between two nodes, the 
orbital direction is not so oblique to the ecliptic but more 
nearly parallel, at which time the shadow moves in a 
more horizontal direction, as explained in observing the 
^'harvest moon." 
Third night. Third night — crescent a little wider and moon set still 
later. It has been said on a previous page that a high 
moon may run below the ecliptic and a low moon above, 
and that the terms '^high" and '^low" relate to the 
High and equator Only. You will find in your almanac that the 
^^' moon runs high and low every two weeks alternately. 

Possibly the pupil may ha,ve gained the impression that 
the moon runs high all winter and low all summer, in 
w^hich case there would be a season of medium declina- 
tion, as in the case of the sun at the equinoxes. This is 
an opportune moment to illustrate these facts of differ- 
ent meridian altitudes of the moon's courses. 



Chas. W. Holbrook's Lunar Tellurian. 93 

The apparent course of the sun is at the plane of the 
echptic, yet the sun is high during summer and low 
during winter, why then should not the moon follow 
nearly the same course, since its path is so nearly the 
same as that of the sun ? Because the entire variation 
of the sun's declination is accomplished during the pass- 
age of the earth through the entire circle of its orbit, 
and this maximum difference requires a year, as shown 
with the tellurian: whereas, the moon passes entirely 
around the earth in one month. Illustrate with the 
lunarian; sun and moon in conjunction July 10th. The High and 

. , . ^ low moon. 

solar and lunar indexes both indicate a high latitude 
upon the globe, and, in fact, both .are high; but the 
moon is not visible and in popular parlance '' there is no 
moon" Now advance the moon to July 16th — arm 
above the subject of Yirgo. Rotate the earth slowly and 
observe that when the United States is at noon the moon 
is one quarter circle beyond. As you rotate the globe 
toward the east you will notice that the lunar index 
which, only a week previously, gave a height of 25 de- 
grees north now gives nothing. That is to say, on the 
day of July 9th, the moon had an altitude equal to the 
sun's, whereas, a week later her declination has receded 
from the Tropic of Cancer to the equator ; a variation 
equal to that of the sun in three months' time. Advance 
the moon to Capricornus — a difference in one more 
week of 30 degrees; showing that the moon's altitude 
is quoted for night season only, by popular voice, while 
the astronomical signs are given for the two points of 
opposition and conjunction. Thus, by pursuing this 
branch of lunar study you will find that when the sun is 
high the moon is low and vice versa. July 1 6th, seventh 



94 Chas. W. Holbrook's Lunar Tellurian. 

night. Moon sets at quarter past twelve in the morning 
in the last of Virgo — sun at date — arm directly above 
the virgin. Adjust the day circle, observing that it 
divides the bright half of the moon in two parts, one 

Quarter part being visible to the earth. On that night the quar- 
ter moon is visible at sunset; at a meridian altitude, set- 
ting far to the southward. For several nights it rises 
later and "waxes" from the '' quarter " to ^'gibbous" 
(which means more than half and less than whole), from 
gibbous to full, which phase brings us to July 23d. 

Fourteenth Fourteenth night. Full moon at a node, in first Saajit- 

night. ^ ^ 

tarius — advance arm to name and place sun at date. 
Full moon. As the moon approaches the descending node it enters 

the penumbral shadow at the lunar ecliptic limit, at 10 

p. M. ; reaching umbra an hour later. 

We have learned why totality does not occur until the 

moon has passed more than its full diameter into the 

shadow, and in this case totality does not occur until 12 

o'clock; lasting an hour and three quarters. 

At half past two in the morning the moon passes out 

of the total into the partial shadow, and into sunlight an 
Eclipse of hour later. The mamitude of the eclipse is 1.825 of 

the moon. ^ ^ 

moon's diameter. 

Where is this eclipse visible ? 

To the larger part of the world except Eastern Europe 
and Asia. 

Illustrate with the lunarian; rotate the globe, bringing 

the United States into sunset position over Libra; sun 

at July 23d. Set the polar index to 7.30 at the circle of 

Where visi- fip;ures — not the numerals. Observe that at this hour 

ble. ^ 

of our sunset, it is near the time of sunrise at Eastern 
Europe and Asia, and at those regions it is past the time 



Chas. W. Holbrook's Lunar Tellurian. 95 

of moonset. It is midnight at Western Europe, and 

those countries are, by the rotation of the earth, within 

its shadow. The moon being also within that shadow 

they are enabled to see the eclipse. And we who reside 

in America are not able to see the eclipse until we too 

are rotated into the shadow. Before Eastern Europe 

and Asia can make the diurnal circuit and reach the 

shadow, or iiight time, the moon has passed beyond and Duration ^of 

the eclipse is over. 

AYe have learned that all eclipses depend upon the posi- 
tion of the moon in its orbit; that they can only occur 
when that orbit crosses the plane of the ecliptic — viz. : 
at or near a node; that the nodes or places of crossing 
recede, on account of the advance of the earth along the 
plane; that eclipses occur only at opposition and con- 
junction of moon and sun. 

it is plain, therefore, that if at the time of the eclipse 
just described the moon's descending node had occurred 
at Virgo or Libra, its course when reaching Capricornus 
would have been so far below the plane as to carry it 
below the shadow of the earth. In that case we would 
see the full moon rise far to the south, but no eclipse. 

If the node at Libra were ascendwg, then the lunar >ioon above 

"^ ^ or below the 

course would be above the earth's shadow and outside eanh. 
the lunar ecliptic limit. 

To resume the lunar journey; — after the full moon the 
illuminated disk appears to shrink, rising later each 
night until July 30th. 

Twenty-first night — last quarter moon in first of Aries Last quar- 
— sun at date. Place the moon over the name and note 
that at the time of our sunset the people of Arabia see 
the quarter moon nearly in their zenith while to those who 



96 Chas. W. Holbrookes Lunar Tellurian. 



Eclipse 
the sun. 



Moon's 
shadow- 
falls hig] 
or low. 



live in Prussia the moon is "low ''; both countries see it 
until sunrise, whereas we do not see it until midnight. 
As the moon wanes from last quarter to new it is to us 
a '' morning moon " and is visible until Aug. 4th, after 
which time the sun's light is too strong and it disap- 
pears. Now if the moon had made a node at quadrature, 
we would not see it again until Aug. 10th, but it is ap- 
proaching a node and a possible eclipse, 
of Aug. 7th — New moon in the middle of Cancer — sun 
at date — place the arm over the crab and observe that, 
as the ascending node occurred Aug. 6th, the lunar 
course carries the moon so far above the plane that the 
lower limb crosses the upper limb of the sun, the shadow 
touching the earth at its north polar extreme ; causing a 
partial eclipse of the sun visible only to Northern Nor- 
way and Sweden. 

At the time of the previous eclipse, July 9th, the node 
occurred after the transit and the m^oon's course was far 
enough below the plane to send the shadow across the 
Antarctic regions. At the time of the eclipse of the 
moon July 23d, the node occurred in the middle of the 
shadow, at exact opposition, thereiore, the eclipse was 
visible to nearly the whole earth. 



Solar and 

lunar 

forces. 



Tides. 

The earth is mostly covered with water. Both sun 
and moon exert great powers of attraction upon the 
earth. We have observed, in studying the causes of the 
precession of the equinoxes, how they pull at the equa- 
torial protuberance, causing the earth to revolve. Their 
power of attraction upon water varies on account of 
disparity of distance ; the moon exerting the most force. 



Chas. W. Holbrook's Lunar Tellurian. 97 

The effect of attraction is to raise the waters of the 
earth above their normal level ; thus, if the earth were 
entirely covered with water there would always be under 
the vertical rays of the sun a wave, or swollen mass. 
Under the moon the same thing would occur in greater 
degree, and these waves would behave in a strange man- 
ner. The solar wave would remain still, the lunar wave 
following the moon around the earth. At times of solar 
eclipse, these forces would unite into one great wave. 
When sun and moon were in opposition, or a lunar 
eclipse should occur, there would be one great swelling 
liquid wave on both sides of the earth, the lunar wave 
being much the greatest. But neither sun. moon, nor 
both combined could draw the water from the side of 
the earth farthest from them ; there would, therefore, 
always be apparently two waves. If sun and moon were 
pulling together, their wave would be the greatest. At 
the extreme limits of attraction the water would be less 
deep, because it had been drawn away to make the wave, 
while upon the hemisphere in darkness the water would 
stand at a normal level. This is precisely what happens 
in nature. The waves are called lides. 

Illustrate with the tellurian ; place the globe upon the illustration, 
geared arm as in cut 1, and the moon upon the central 
post at T ; put on the day circle with the hoop C bent 
downward to horizontal beyond L. Place the night 
shade on the side toward the moon, the sun at a distance 
from the earth and on opposite side to the moon. The 
moon will exert an attractive influence greater than the 
sun, as the protuberance of the n'ght shade is greater 
than that of the hoop. Rotate the arm and the earth 
will be revolved from west to east, the tides from east 
7 



98 Chas. W. Holbrookes Lunar Tellurian. 

to west. Wander along the ocean beach and you will 

Full and niark the rising and fallins: tides twice a day. When at 
ebb tides. o o j 

their height, they are "full tides," when at their low 
mark, they are ^'ebb tides." This refers simply to their 
daily action. When the moon is new, or full, the tide is 
higher than the daily average, and is called " spring 
tide." V7hen the moon is in quadrature the water ebbs 
lower, and rises not so high as the average flow, and is 
called ''neap tide." 

The general action of tides is much modified by the 
configuration of the coasts which the approach, or rather 
which approach them. In mid -ocean, tides are not dis* 
cernible. In gulfs having broad openings in the direc- 
tion of the advancing tidal wave, tides will rise higher 
at the western shores, but will not ebb so much, leaving 
the relative distance between a full and ebb tide about 
the same. Gulfs having their openings at the west will 
not feel the effect of the tides unless they are large 
bodies, like the Mediterranean Sea, having sufficient 
Variation, volume to respond to the attractive force. In the sea 
just named, the tide varies but three feet; while the 
German Ocean receives the onflow of the Atlantic tides 
through two gates — the North Sea and English Chan- 
nel — doubling the system and giving them four tides a 
day. The great variation of tide at Bay of Fundy has 
two causes. 1 . The advancing wave across the Atlantic 
is increased by the opposing force of the Gulf Stream. 
2. The increased wave, reaching the large gulf, is sud- 
denly brought to head by the shore resisting and pen- 
ning it in. The water cannot flow onward nor escape , 
it must rise. And it does, to such a height that the 
observer may see the tops of a ship's masts at wharf in 



Chas. W. Holbrook's Lunar Tellurian. 99 



New Brunswick at low tide, and the hull of the ship 
moored to the same level a few hours later. Inland seas 
have little or no tide. 

Tides are greater when the moon is in perigee than 
when in apogee. The earth's perihelion or aphelion also 
affects the tides. The greatest attainable height of a Greatest 
tidal wave must, therefore, occur under these conditions 
— viz., the earth at perihelion ; the sun totally eclipsed, 
at a node very near an equinox, by the moon in perigee. 

Figures denoting tidal rise and fall are deceptive. 
For example, the rise of seventy feet in the Bay of Fundy 
is only a rise of thirty-five : the other thirty-five is the 
fall. Let 1 =: the normal height of the water ; a wave 
of 35 feet in height approaches, followed by a fall of 35 
f^et to level and 35 feet more to make a rise at some 
other locality ; 35+35 = 70. A vessel at sea will 
mount the crest of a wave thirty feet high, but part of 
the wave's measurement must be given to the trough in 
which the ship rides before mounting The trough is 
below, the crest above the normal level ; the measure- 
ment of both equals the amount of displacement, so to 
speak. Tides follow the vertical direction of the moon 
after an interval. Water, though elastic, does not 
respond to gravitation instantly, and in all ports of com- 
merce the times of tides are tabulated and published. 

Tides are considerably affected by winds. A tidal Result of 

'^ -^ winds. 

wave accompanied by a strong, steady breeze will be 
lower in mid-ocean and higher at the western coasts, 
for the wind will not only accelerate it but will -pile it up 
and retard its ebb not only as to time, but as to quantity. 
A tidal wave opposed by a strong wind will be higher in 
mid-ocean and lower at shore ; its ebb will be accelerated 
and increased. 



100 Chas. W. Holbrook's Lunar Tellurian. 

A wind blowing up a considerable river will cause a 
rue but not a tide, for tides are regular by cause and in 
effect. The writer, when a lad, was aboard a steamer 
which ran aground in the Potomac River during a neap 
tide accompanied by a strong breeze. The propulsive 
power of the wind raised the water to the height of a 
'- spring " tide. The question was, would the next spring 
tide float the vessel ? It did not. The succeeding spring 
tide did, however, as it was accompanied by a strong 
breeze. 

Tides and their changes are very important to com- 
merce. As a rule, . great bays are divided from the 
ocean by lines of shoals extending across their mouths. 
At normal tide a vessel may not be able to enter on 
account of her great draught. By awaiting a high tide 
she crosses the bar and rides safely in harbor where the 
water has greater depth. Ship masters love to sail with 
tide and wind, for then the sea is smoother and speed 
greater. There is nothing more uncomfortable than to 
round a cape against the wind and with the tide, for the 
sea is rough and dangerous with peculiar waves called 
" choppy." Against a rocky coast the incoming tide, if 
assisted by the wind, dashes and beats with great vio- 
lence, sending the spray to great heights and thundering 
its tireless monologue. 



